Andrew Benson's report will be on the website very soon.
Please join us again tomorrow. The final day of pre-season testing 2015 starts at 08:00 GMT.
Final pre-season test, day three times and laps completed
1. Lewis Hamilton (Mercedes) 1:23.022 (76)
2. Felipe Massa (Williams) 1:23.262 (102)
3. Kimi Raikkonen (Ferrari) 1:23.276 (136)
4. Carlos Sainz (Toro Rosso) 1:24.191 (132)
5. Romain Grosjean (Lotus) 1:24.200 (116)
6. Marcus Ericsson (Sauber) 1:24.477 (123)
7. Nico Hulkenberg (Force India) 1:24.939 (158)
8. Kevin Magnussen (McLaren) 1:25.225 (39)
9. Daniel Ricciardo (Red Bull) 1:25.742 (128)
Chequered flag
You can stick a fork in this day of testing. We are all done.
One more day to come tomorrow and then attention can finally turn to the opening race of the season in Australia in a fortnight.
Full times coming up.
F1 journalist Dan Knutson in Barcelona
"Lewis Hamilton, who has done 76 laps, and Kevin Magnussen, who did 39, are the only two drivers not to complete over 100 laps today."
Red flag
Carlos Sainz, moments after posting his best time of the day, slows to a halt at turn three.
Super-soft shake-up
As before lunch, we have a few drivers out there on the super-softs looking for some Hollywood times.
Carlos Sainz is one of those in the Toro Rosso, going fourth with a 1:24.191.
Lotus' Romain Grosjean is up to fifth after a 1:24.200 on the same tyre.
F1 journalist Dan Knutson in Barcelona
"Honda F1 boss Yasuhisa Arai and McLaren racing director Eric Boullier have just finished a media briefing, following the curtailment of their day's running with an oil leak. Boullier said the situation was 'not so negative or disappointing' because 'we were not expecting to cover 100 laps every day'.
"As for the Australian Grand Prix in two weeks' time, Boullier said: 'We won't be as ready as we'd like but we will do our best.'"
Green flag
Ericsson's car is taken away and we're off again.
Red flag
Marcus Ericsson has stopped his Sauber at turn three.
My car's prettier than yours - #bbcf1
We're asking which car you think is the looker of 2015.
Dan White: "It's got to be the Mercedes.... Looks a little like the 2006 McLaren from the front, with its thin nose section."
anthony wyatt: "Force India or Sauber. Can't make me mind up. That's an OAP for you."
Charles Crook: "Of the current lot the black and white Red Bull is the best looking, even if its just a temporary paint job."
Androsid: "Force India is one #beautifulbeast"
Of course, the discussion via #bbcf1 quickly turned to classics of the past, with the Jordan 191, Benetton B194, Arrows A20 and the JPS Lotus all getting shout outs.
Jo Lantru even suggested the stunning motor below. I'm not sure we can accept this one though.
BBCCopyright: BBC
Hamilton goes quickest
As we enter the final hour the gloves come off and Lewis Hamilton immediately jumps the Mercedes to the top of the pile.
On the soft tyre, the world champion does a 1:23.022, two-tenths faster than the previous best today by Felipe Massa, which don't forget was a lap done on the super-soft Pirelli.
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One hour left
Sadly we've not had too much in the way of tumbling lap times to report with the teams switching to longer runs since lunch.
Still, here's where we're at. The times have not change much since the break but note the number of laps piled on.
1. Felipe Massa (Williams) 1:23.262 (102 laps)
2. Kimi Raikkonen (Ferrari) 1:23.276 (125)
3. Lewis Hamilton (Mercedes) 1:23.648 (61)
4. Marcus Ericsson (Sauber) 1:24.477 (103)
5. Nico Hulkenberg (Force India) 1:24.939 (143)
6. Kevin Magnussen (McLaren) 1:25.225 (39)
7. Daniel Ricciardo (Red Bull) 1:25.742 (111)
8. Romain Grosjean (Lotus) 1:27.950 (105)
9. Carlos Sainz (Toro Rosso) 1:26.330 (121)
Williams call time on Massa's pre-season
Williams tweet: "And that's day [three] finished for us and @MassaFelipe19's winter test programme completed. Next stop Melbourne."
Well not quite. Bottas has to have another go tomorrow.
Magnussen: 'Great to be back'
Kevin Magnussen on Twitter: "Great to be back in the car today. The #McLarenHonda feels great! Plenty more to come from this one. Thanks for all the support today guys!"
Hair-raising time for Carlos
Toro Rosso tweet: "And this is what happens when you take your helmet off after 121 laps!! @carlosainz #HelmetHair"
Toro RossoCopyright: Toro Rosso
The lovely, lovely Sauber
Did I mention that I like the look of the new Sauber C34? Because I do. Very much. Nice shade of blue.
In fact, the wholesale winter rhinoplasty undertaken on those hideous 2014 noses has resulted in a rather handsome bunch of F1 cars.
Let me know your favourite of the new breed using #bbcf1.
Getty ImagesCopyright: Getty Images
Confirmation from McLaren
McLaren tweet: "An oil leak has stopped play, so that's a wrap for today. We'll be back tomorrow for more #F1Testing."
"Oh dear. Just when things were suddenly looking up for McLaren, they hit another problem.
"After Jenson Button completed 101 laps on Friday and Kevin Magnussen another 38 this morning with no issues, it was beginning to look as if they might - just might - have got over the hill on the reliability front.
"But after the eagle-eyed Ben Edwards spotted that Magnussen's car had been wheeled back into the garage trailing fluid, the team have now called it a day.
"That fluid was oil, from a leak. McLaren now have just eight hours' running to sort themselves out before first practice at the Australian Grand Prix."
Day over for McLaren
Ben Edwards' mince pies didn't fail him.
There was indeed a leak on the McLaren. Oil to be precise.
Game over after just 39 laps. Tough on Kevin Magnussen.
Whither Kev?
Now that Mercedes are back up and running the wooden spoon for laps completed has passed to McLaren.
Kevin Magnussen has done just one lap since lunch, moving his tally to 39. The 100 laps done by Jenson Button yesterday does not look in danger of being emulated.
Worth remembering, of course, that BBC commentator Ben Edwards reported a fluid leak on the MP4-30 earlier (see 13:36).
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What of Red Bull?
I don't seem to have typed out the words Red Bull or Daniel Ricciardo much today, so I should probably check in with them.
The Australian has very quietly got on with putting up 94 laps in the RB11 today, although his best time of 1:25.742 is good only for seventh place.
He's has not, however, indulged in any soft-tyre laps, so when he does you can expect the Red Bull to climb the order.
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Hamilton back on track
Mercedes have completed their "experimental" set-up work and Lewis Hamilton is out on track for the first time in a good few hours.
He's on the medium tyre and does a 1:30.327 followed by a 1:26.686.
We'll watch the progress of the experiment with interest...
MercedesCopyright: Mercedes
Ton up Hulk
Force India on Twitter: "That's a century! 100 laps on the board for Nico who keeps putting mileage on the VJM08. And on he goes..."
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F1 journalist Dan Knutson in Barcelona
"Carlos Sainz and Kimi Raikkonen are both doing race simulations and were running fairly closely together on the track. Sainz was ahead, but Raikkonen closed in and overtook him."
'This is testing'
Toro Rosso tweet: "Laps and more laps. This is the 80th time that @carlosainz crosses start/finish line. More to come, this is testing!"
Toro RossoCopyright: Toro Rosso
Century on the board for Kimi
Kimi Raikkonen's race-simulation work for Ferrari has made him the first driver to stampede into three-figure territory.
He's on 106 laps and still the figure is climbing. With two and a half hours left in the day that Ferrari could truly clock up some serious mileage today.
The Force India of Nico Hukenberg is also about to bring up lap number 100.
"Ferrari's Kimi Raikkonen appears to be on a race-simulation run this afternoon. It will be fascinating later to compare his times with those of Hamilton and the two Red Bull drivers last week."
Oh all right, one more from the archive
Damiano has been in touch using #bbcf1 and points out that there may be pictures to rival the earlier one of Graham and Damon Hill. The below example being one of them.
He's probably right.
Reading left to right, we have Bruce McLaren (100 grands prix, four wins), Stirling Moss (66 grands prix, 16 wins), Tony Brooks (38 grands prix, six wins), Graham Hill (two titles, 176 grands prix, 14 wins), Jo Bonnier (104 grands prix, one win) and Wolfgang von Trips (27 grands prix, two wins), with young Damon (one title, 115 races, 22 wins) at centre, on 17 July 1961.
That's three world titles, 511 races and 65 wins right there, folks. #calculator
Tragically, Ferrari driver Von Trips would die less than two months after this photograph was taken, killed in an accident at Monza while leading the championship. His team-mate Phil Hill went on to take the title, with Von Trips a posthumous runner-up by one point.
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F1 journalist Dan Knutson in Barcelona
"Williams technical boss Pat Symonds talked with the media this afternoon. He is pleased with the progress that Williams has made in winter testing.
"He said: 'So far it has gone quite smoothly. As the testing restrictions get harder and harder you have to become more and more disciplined in the way you test. You have just 12 days to cover all the reliability, all the systems, and start looking at performance. Thus far it has gone absolutely on plan - we have not had to change anything. We have got through all the work we planned to do by this stage. We have not spent a lot of time chasing performance in the car. In fact in the first two tests, absolutely nothing in the performance way. At this final test we are now just starting to exercise it a little bit and see what we can get out of it. It looks reasonably promising at the moment. There is still a way to go.'
Get involved - #bbcf1
Henry Evans: "So merc are still in a league of their own... BUT can't wait for the battle behind! Ricciardo vs Vettel vs Bottas = Tasty."
Michael Powell: "V impressive reliability from Force India after only starting to run 2015 car yesterday. Dark horses for a good points haul in Aus?"
David Boyle: "Towards the end of tomorrow's testing, McLaren to turn the Honda engine up to full capacity and set the fastest lap."
Peter Smith: "I've always supported McLaren and look forward to the new Honda partnership, but that Force India looks amazingly improved, well done."
Heath Brett: "Shame the Mercs look so far ahead again, and I can't see any epic battles between Rosberg & Hamilton to liven things ZZzzzz!!!!"
F1 journalist Dan Knutson in Barcelona
"Christian Horner has headed off on a motor scooter. He's no doubt going out around the circuit to see how the Red Bull RB11 goes through the corners."
Still no sign of Mercedes and Hamilton
Mercedes reported in the hour before lunch that they would be making some "experimental set-up changes" before hitting the track again.
Well, whatever that experiment is it's still ongoing.
They've now lost 90 minutes of track time to it and Lewis Hamilton remains mired on just 36 laps for the day. For comparison, Kimi Raikkonen has put up 78 laps and counting for Ferrari.
Getty ImagesCopyright: Getty Images
Like father, like son
Just returning briefly to Graham Hill and Damon Hill.
There is of course only one picture that truly epitomises the only father and son to each become F1 world champion, and it's this cracker from 1964.
Getty ImagesCopyright: Getty Images
And maybe trouble for Lotus too?
Ben Edwards
BBC F1 commentator
"Some puffs of what looks like oil smoke from back of Lotus on this lap."
Problems at McLaren?
Ben Edwards
BBC F1 commentator
"I'm just in front of the McLaren garage. Magnussen was due to come in and go straight out (they moved me out of way) but then he stopped just before the box, they had to wheel it back in and fluid had leaked onto ground which they're now cleaning up. Looked more like coolant than oil but not sure."
"Also just beginning to see some clouds forming overhead after a beautifully clear morning."
Dress bantz from Williams
Williams tweets: "Pat confirms the #FW37 is white and blue not #blackandblue or #whiteandgold although it has got some red #bandwagon"
WilliamsCopyright: Williams
Massa and Kimi settle in for longer runs
It's been a slow-burner since the restart.
Felipe Massa is doing a long run on the hard tyre for Williams, while Kimi Raikkonen is also going long for Ferrari on the medium.
Kevin Magnussen in the McLaren briefly joined them but came straight back into the pits.
F1 journalist Dan Knutson in Barcelona
"Romain Grosjean talked with the media during the lunch break. The 2015 Lotus is a much better car than last year's E22. 'You can push it hard trying to find the limit,' he said."
knutsonCopyright: knutson
Who, what, where, when? Bonus round answer
This one didn't fool too many either.
Graham Hill, the world champion of 1962 and 1968, sits astride his motorbike as he chats with son Damon, who would become champion himself in 1996.
Dan Brown was among those to get in touch with the right answer. He also correctly said the pic was taken in 1975 AND that the bike is a Bultaco Alpina (I'll take your word on that one).
Felipe Massa, quickest this morning, bounds straight onto the track like an eager puppy.
Magnussen settling in
Honda tweet: "With each session, @KevinMagnussen is getting faster, and more comfortable with the #MP430."
HondaCopyright: Honda
Who, what, where, when? Bonus round
Right, this one is slightly different as it's away from the track and there's no cars.
However, there are two F1 world champions in the picture here. Can you tell me who they are? The year's not needed, but I'm open to being impressed.
#bbcf1 please.
Getty ImagesCopyright: Getty Images
Who, what, where, when? The answer
Thanks for playing along. I think that caught quite a few out but I'd say around 70% of you still got it right. Impressive.
The answer was Williams' Thierry Boutsen winning the Australian Grand Prix in the rain, 1989. Craig Wilson was quickest with the right answer.
As it's Saturday I'll do one more.
Two mins...
Getty ImagesCopyright: Getty Images
Force India continue to make up for lost time
Force India tweet: "End of the morning session. Nico was the busiest driver so far, with 76 laps, just one short of yesterday's total."
Force IndiaCopyright: Force India
Who, what, where, when?
Ok, here we go. I was soundly put in my place yesterday for underestimating the depth of the F1 knowledge out there, so I'm going for a bit of a random one today (cue another 99% success rate).
So, tell me who this driver is, who he's driving for, what is going on, and at which track and in which year.
"Well, that was a properly fascinating morning of testing. Felipe Massa and Kimi Raikkonen have grabbed the headlines, but there is no mistaking the overall message that Mercedes appear to have a sizeable advantage.
"Meanwhile, in the context of their winter struggles, it was another encouraging morning for McLaren, with Kevin Magnussen doing 34 laps to add to the 101 Jenson Button managed on Friday, and with no apparent problems. Have Honda finally nailed the reliability of that engine?
"Pace-wise, though, it's not looking great for McLaren at the moment. A 1:25.225 on the softs is pretty slow - 2.5secs off a Mercedes and 1.3secs off a Williams - unless Magnussen did that time on a lot of fuel. But Magnussen would have to had 60kg of fuel in the car - unlikely on a short run - to make that competitive with a Mercedes.
"For McLaren's sake, let's hope the engine is still turned down at this stage."
Chequered flag
Lunchtime. We're done for the morning here in Barcelona.
Times coming up.
Ericsson and Hulkenberg improve on super-softs
The Sauber of Marcus Ericsson displaces goes third with a lap of 1:24.477 on the super-soft.
Force India's Nico Hulkenberg also has the red-walled tyre on and goes fourth with a 1:24.939.
Quiz time approaching
Just to mark your cards for some upcoming lunchtime buffoonery. I'll do my usual thing of blurring famous moments in F1 history and you have to tell me who is in said picture, as well as when and where it was taken.
BBCCopyright: BBC
Top three as lunch looms
1. Felipe Massa (Williams) 1:23.262 (set on super-soft tyre)
"These recent fast times set by Felipe Massa in the Williams and Kimi Raikkonen's Ferrari fit exactly the pattern that has emerged over the last few days. Both setting a 1:22.3 on super-softs, they are still 0.5secs short of the time set on soft tyres by Nico Rosberg's Mercedes on Friday - and the softs are at least that margin slower than the super-softs.
"There is more and more evidence that the Mercedes has an advantage of about a second over the other teams and that Williams, Ferrari and Red Bull are exceptionally closely matched behind, even if we are yet to see a qualifying-type lap from the Red Bull this week."
McLaren bares its teeth
Kevin Magnussen has hauled the McLaren up to third place in among this pre-lunchtime frenzy. A 1:25.225 on the soft tyre is the team's best effort of the week, eclipsing Jenson Button's 1:25.590 yesterday.
Raikkonen breathing down Massa's neck
Ferrari's Kimi Raikkonen has joined Felipe Massa in the hooning joys of a set of super-softs and lobs in a 1:23.276, just 0.014secs off the Williams man.
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F1 journalist Dan Knutson in Barcelona
"The Ferrari mechanics run hither and thither with the screens trying to hide the car when Kimi Raikkonen brings the car into the pits. There must be some new parts on it today."
KnutsonCopyright: Knutson
Massa raises the bar once more
Felipe Massa's Williams is now sporting a set of super-soft tyres and his lap times are duly falling - he's just done a 1m23.262s. That's still half a second off Nico Rosberg's time on the softs for Mercedes yesterday.
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Get involved
As always we need your observations on today's testing action. Send us your comments using #bbcf1.
Change at the top
Felipe Massa, who has the second fastest time of the Barcelona tests so far, jumps to the top of the order today with a 1:24.950 in the Williams FW37. That's a medium-tyre run, and is some 1.5secs down on his best time of the test, which came on the faster soft tyre.
Quarter of a century for Magnussen
McLaren on Twitter: "The track's warming up and there's blue skies overhead. 25 laps on the board for Kev."
McLarenCopyright: McLaren
The Hulk goes third
Still the Force India powers on. I don't think it's had a single glitch since it came out the wrappers yesterday.
Nico Hulkenberg is now up to third place after a 1:26.137 on the soft tyre.
F1 journalist Dan Knutson in Barcelona
"McLaren is running the Melbourne-spec Honda engine today, according to sources."
It is understood the Honda engine has been running at a limited capacity in testing so far, so this may indicate the unit is at 100% power today. Of course, only McLaren and Honda know the truth!
Sainz sets a time
It looks like pit stop practice is over at Toro Rosso.
Carlos Sainz goes out and puts up a 1:27.823 on the medium tyre, good for seventh place.
"Lovely catch up with Massa and Bottas at Williams. Good atmosphere in the team. Great coffee too. Feeling a little more awake now."
F1 journalist Dan Knutson in Barcelona
"Toro Rosso and Carlos Sainz are doing pit stop practice. It's an important element of pre-season testing. Jenson Button said yesterday: 'We did pit stop practice and we did practice starts. We have not done a lot of that in winter testing. So those sorts of things you need to work on as well, not just the performance of the car.'"
Toro RossoCopyright: Toro Rosso
Force India on the move
We've been bigging up the promise of the new Force India after its showing on debut yesterday, and now the speed is starting to show through.
Nico Hulkenberg has pinged the VJM08 into fifth place with a 1:27.404, within two seconds of the pace-setting Mercedes on the same tyre.
Magnussen on the board
McLaren's Kevin Magnussen has finally clocked a time, a 1:29.336 on the medium Pirelli. The Dane, who lost his drive this season to Fernando Alonso, is up to 12 laps.
That leaves Toro Rosso's Carlos Sainz as the last man still to set a time, although he has done 18 installation laps.
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Two hours gone
Here's your top three check:
1. Lewis Hamilton (Mercedes) 1:25.471 (30 laps)
2. Daniel Ricciardo (Red Bull) 1:25.941 (27)
3. Kimi Raikkonen (Ferrari) 1:26.532 (22)
Hamilton goes faster
Lewis Hamilton sets a new fastest lap of the day for Mercedes. On the medium tyre he posts a 1:25.471.
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New Force India powers on
Force India tweet: "Flying visit to the pits for Nico and the VJM08. A few quick adjustments and we're on our way again."
Force IndiaCopyright: Force India
Nico Hulkenberg has done 37 laps today with a best time of 1:29.277.
It's all gravy (train)
Lotus tweet: "Nose change for @RGrosjean - all part of the aero evaluation gravy train."
LotusCopyright: Lotus
Day two times recap
It's probably worth you having yesterday's times to hand. Y'know, for reference.
At the moment the best times today are some three and a half second off Rosberg's howitzer yesterday, so plenty of scope for improvement.
1. Nico Rosberg (Mercedes) 1:22.792 (106 laps)
2. Valtteri Bottas (Williams) 1:23.995 (90)
3. Felipe Nasr (Sauber) 1:24.071 (141)
4. Sebastian Vettel (Ferrari) 1:25.339 (143)
5. Jenson Button (McLaren) 1:25.590 (101)
6. Pastor Maldonado (Lotus) 1:26.705 (140)
7. Max Verstappen (Toro Rosso) 1:26.766 (139)
8. Daniil Kvyat (Red Bull) 1:26.965 (84)
9. Nico Hulkenberg (Force India) 1:28.412 (77)
35 million cans of Red Bull
No, that's not the answer to the question, "what does it take to survive nine hours of blogging on F1 testing?"
It is in fact the distance Toro Rosso have gone in testing, as this tweet explains: "As @carlosainz completes lap 10 of day, it's 1000 laps in testing: 4573kms, nearly 35 Million @redbull cans in a row!"
Toro RossoCopyright: Toro Rosso
F1 journalist Dan Knutson in Barcelona
"There are only two more days of the permitted 12 preseason testing days to go. What a difference to years gone by when there were no limits on testing and the big teams would test for days on end."
KnutsonCopyright: Knutson
One hour gone
Right, the lads have been out there for 60 whole minutes now. Here's the top three as it stands.
1. Lewis Hamilton (Mercedes) 1:26.110 (20 laps)
2. Kimi Raikkonen (Ferrari) 1:26.532 (19)
3. Felipe Massa (Williams) 1:27.271 (12)
Magnussen hits the track
Just as we were starting to wring our hands over McLaren, Kevin Magnussen noses the MP4-30 out of the garage to complete an installation lap.
"Finally, McLaren have done some miles. In one day on Friday, Jenson Button managed 100 laps - that is pretty much exactly half the entire total of their previous running throughout nine previous days of testing.
"McLaren are still way behind their key rivals in terms of understanding their car - Mercedes have been doing that sort of mileage every day - but as Button said: 'It's a starting point.'
"He added: 'It's a shame we've missed so many days, but were on the right track now and it's definitely progress. We have a lot of work to do still. We know we're not the quickest guys out there. We have a lot of work to do with set-up and getting the maximum out of the power unit, but you'll see a lot of improvements out of us before Melbourne.'"
Getty ImagesCopyright: Getty Images
Mileage mounts up
Some of these guys aren't hanging around today. The times are nothing special but the miles are already mounting up.
With just over half an hour gone, Kimi Raikkonen's Ferrari has done 16 laps, the Force India of Nico Hulkenberg 14, Lewis Hamiton's Mercedes is on 15 and the Red Bull of Daniel Ricciardo 10.
The only car not to set a lap is that of McLaren's Kevin Magnussen. After completing 100 laps with Jenson Button at the wheel yesterday, let's hope this is not a sign of fresh problems for the team.
"Force India had to wait until three days before the end of testing to run their new car, its build delayed by cash-flow problems. But at least when it ran, it did so flawlessly, Nico Hulkenberg completing 77 laps in one afternoon.
"As the driver himself said: 'That is quite remarkable.' Performance-wise it was nothing to write home about, but first days are always about box-ticking. There were a lot of baseline checks today and getting a feel for the car.'
"The German has another go on Saturday before handing over to team-mate Sergio Perez for the final day on Sunday."
"You didn't have to be a psychologist to realise from the tone in Williams driver Valtteri Bottas's voice that seeing Nico Rosberg's pace had been a dispiriting experience. 'It's pretty quick,' the Finn said. 'I think everyone was a little bit surprised. Everyone knew they were quick. But they are very quick. But that's how it is.'
"So much was revealed in those few words. Regardless of the fuel load Rosberg was on, we now know Bottas must have been pretty low on fuel - otherwise he would not have been so concerned about the Mercedes' pace.
"So now there is more or less a benchmark for a Williams performance, and from that much more can be extrapolated. But the key thing seems clear. Mercedes are, again, miles ahead."
Getty ImagesCopyright: Getty Images
First time on the board
It's been a predictably steady start to the day with temperatures so low.
The Williams of Felipe Massa sets the early benchmark, a 1:27.271 on the soft compound.
Today's drivers
In no particular order, we have Romain Grosjean (Lotus), Marcus Ericsson (Sauber), Lewis Hamilton (Mercedes), Daniel Ricciardo (Red Bull), Kimi Raikkonen (Ferrari), Felipe Massa (Williams), Nico Hulkenberg (Force India), Carlos Sainz (Toro Rosso), Kevin Magnussen (McLaren).
Mercedes 'looks nailed to the track'
Ben Edwards
BBC F1 commentator
"I was watching the cars out on track for a time on Friday. The Mercedes looks nailed to the track, with brilliant turn-in to the corners. It's no surprise they have been looking so fast.
"Of the rest, I'd say the Williams probably looks second best, while the Ferrari also looks reasonably good. The drivers can get on the power reasonably early, which is a good sign for the Italian team as traction has been one of their problems in recent years, but the turn-in is still not as sharp or decisive as they might want.
"The McLaren looks OK, too - although we know they were running down on power. Unfortunately, the Red Bull did not do many laps while I was out there."
Getty ImagesCopyright: Getty Images
Chilly morning in Barcelona
There was a frost on the ground around the Circuit de Catalunya today, and F1 journalist Dan Knutson in Barcelona informs us it is indeed a bracing morning.
"Clear blue skies with an air temperature of 3.4 degrees Centigrade and a temperature of 13.9 degrees Centigrade. There is a zero percent chance of rain today," he says.
"If there were any doubts about who was leading the way ahead of the new Formula 1 season - and among the teams and drivers there were not really - they were finally expunged on Friday.
"Nico Rosberg set a new fastest time of the winter, on the first outing for Mercedes on the soft tyre. He was quickest by 1.2 seconds on the day, from Williams's Valtteri Bottas, and by 0.7secs over the previous fastest time, set by Williams's Felipe Massa. That compares with the 0.8secs advantage Lewis Hamilton had on a race simulation run at the last test over the Red Bull and Williams.
"One leading team boss told BBC Sport he thought Mercedes had a one-second margin over the rest earlier this week.
"Everyone ready for Hamilton v Rosberg part II?"
Good morning
Welcome to the penultimate day of pre-season F1 testing for 2015.
Nico Rosberg rather let the cat out of the bag yesterday as Mercedes' searing pace was shown up with a quite brilliant lap on the soft Pirelli tyre.
Can the other teams respond? Well, we should find out over the next few hours.
Live Reporting
Jamie Strickland
All times stated are UK
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Latest PostCheerio
Thanks for your company and contributions today.
Andrew Benson's report will be on the website very soon.
Please join us again tomorrow. The final day of pre-season testing 2015 starts at 08:00 GMT.
Final pre-season test, day three times and laps completed
1. Lewis Hamilton (Mercedes) 1:23.022 (76)
2. Felipe Massa (Williams) 1:23.262 (102)
3. Kimi Raikkonen (Ferrari) 1:23.276 (136)
4. Carlos Sainz (Toro Rosso) 1:24.191 (132)
5. Romain Grosjean (Lotus) 1:24.200 (116)
6. Marcus Ericsson (Sauber) 1:24.477 (123)
7. Nico Hulkenberg (Force India) 1:24.939 (158)
8. Kevin Magnussen (McLaren) 1:25.225 (39)
9. Daniel Ricciardo (Red Bull) 1:25.742 (128)
Chequered flag
You can stick a fork in this day of testing. We are all done.
One more day to come tomorrow and then attention can finally turn to the opening race of the season in Australia in a fortnight.
Full times coming up.
F1 journalist Dan Knutson in Barcelona
"Lewis Hamilton, who has done 76 laps, and Kevin Magnussen, who did 39, are the only two drivers not to complete over 100 laps today."
Red flag
Carlos Sainz, moments after posting his best time of the day, slows to a halt at turn three.
Super-soft shake-up
As before lunch, we have a few drivers out there on the super-softs looking for some Hollywood times.
Carlos Sainz is one of those in the Toro Rosso, going fourth with a 1:24.191.
Lotus' Romain Grosjean is up to fifth after a 1:24.200 on the same tyre.
F1 journalist Dan Knutson in Barcelona
"Honda F1 boss Yasuhisa Arai and McLaren racing director Eric Boullier have just finished a media briefing, following the curtailment of their day's running with an oil leak. Boullier said the situation was 'not so negative or disappointing' because 'we were not expecting to cover 100 laps every day'.
"As for the Australian Grand Prix in two weeks' time, Boullier said: 'We won't be as ready as we'd like but we will do our best.'"
Green flag
Ericsson's car is taken away and we're off again.
Red flag
Marcus Ericsson has stopped his Sauber at turn three.
My car's prettier than yours - #bbcf1
We're asking which car you think is the looker of 2015.
Dan White: "It's got to be the Mercedes.... Looks a little like the 2006 McLaren from the front, with its thin nose section."
anthony wyatt: "Force India or Sauber. Can't make me mind up. That's an OAP for you."
Charles Crook: "Of the current lot the black and white Red Bull is the best looking, even if its just a temporary paint job."
Androsid: "Force India is one #beautifulbeast"
Of course, the discussion via #bbcf1 quickly turned to classics of the past, with the Jordan 191, Benetton B194, Arrows A20 and the JPS Lotus all getting shout outs.
Jo Lantru even suggested the stunning motor below. I'm not sure we can accept this one though.
Hamilton goes quickest
As we enter the final hour the gloves come off and Lewis Hamilton immediately jumps the Mercedes to the top of the pile.
On the soft tyre, the world champion does a 1:23.022, two-tenths faster than the previous best today by Felipe Massa, which don't forget was a lap done on the super-soft Pirelli.
One hour left
Sadly we've not had too much in the way of tumbling lap times to report with the teams switching to longer runs since lunch.
Still, here's where we're at. The times have not change much since the break but note the number of laps piled on.
1. Felipe Massa (Williams) 1:23.262 (102 laps)
2. Kimi Raikkonen (Ferrari) 1:23.276 (125)
3. Lewis Hamilton (Mercedes) 1:23.648 (61)
4. Marcus Ericsson (Sauber) 1:24.477 (103)
5. Nico Hulkenberg (Force India) 1:24.939 (143)
6. Kevin Magnussen (McLaren) 1:25.225 (39)
7. Daniel Ricciardo (Red Bull) 1:25.742 (111)
8. Romain Grosjean (Lotus) 1:27.950 (105)
9. Carlos Sainz (Toro Rosso) 1:26.330 (121)
Williams call time on Massa's pre-season
Williams tweet: "And that's day [three] finished for us and @MassaFelipe19's winter test programme completed. Next stop Melbourne."
Well not quite. Bottas has to have another go tomorrow.
Magnussen: 'Great to be back'
Kevin Magnussen on Twitter: "Great to be back in the car today. The #McLarenHonda feels great! Plenty more to come from this one. Thanks for all the support today guys!"
Hair-raising time for Carlos
Toro Rosso tweet: "And this is what happens when you take your helmet off after 121 laps!! @carlosainz #HelmetHair"
The lovely, lovely Sauber
Did I mention that I like the look of the new Sauber C34? Because I do. Very much. Nice shade of blue.
In fact, the wholesale winter rhinoplasty undertaken on those hideous 2014 noses has resulted in a rather handsome bunch of F1 cars.
Let me know your favourite of the new breed using #bbcf1.
Confirmation from McLaren
McLaren tweet: "An oil leak has stopped play, so that's a wrap for today. We'll be back tomorrow for more #F1Testing."
Bad luck returns to bite McLaren and Honda
Andrew Benson
Chief F1 writer
"Oh dear. Just when things were suddenly looking up for McLaren, they hit another problem.
"After Jenson Button completed 101 laps on Friday and Kevin Magnussen another 38 this morning with no issues, it was beginning to look as if they might - just might - have got over the hill on the reliability front.
"But after the eagle-eyed Ben Edwards spotted that Magnussen's car had been wheeled back into the garage trailing fluid, the team have now called it a day.
"That fluid was oil, from a leak. McLaren now have just eight hours' running to sort themselves out before first practice at the Australian Grand Prix."
Day over for McLaren
Ben Edwards' mince pies didn't fail him.
There was indeed a leak on the McLaren. Oil to be precise.
Game over after just 39 laps. Tough on Kevin Magnussen.
Whither Kev?
Now that Mercedes are back up and running the wooden spoon for laps completed has passed to McLaren.
Kevin Magnussen has done just one lap since lunch, moving his tally to 39. The 100 laps done by Jenson Button yesterday does not look in danger of being emulated.
Worth remembering, of course, that BBC commentator Ben Edwards reported a fluid leak on the MP4-30 earlier (see 13:36).
What of Red Bull?
I don't seem to have typed out the words Red Bull or Daniel Ricciardo much today, so I should probably check in with them.
The Australian has very quietly got on with putting up 94 laps in the RB11 today, although his best time of 1:25.742 is good only for seventh place.
He's has not, however, indulged in any soft-tyre laps, so when he does you can expect the Red Bull to climb the order.
Hamilton back on track
Mercedes have completed their "experimental" set-up work and Lewis Hamilton is out on track for the first time in a good few hours.
He's on the medium tyre and does a 1:30.327 followed by a 1:26.686.
We'll watch the progress of the experiment with interest...
Ton up Hulk
Force India on Twitter: "That's a century! 100 laps on the board for Nico who keeps putting mileage on the VJM08. And on he goes..."
F1 journalist Dan Knutson in Barcelona
"Carlos Sainz and Kimi Raikkonen are both doing race simulations and were running fairly closely together on the track. Sainz was ahead, but Raikkonen closed in and overtook him."
'This is testing'
Toro Rosso tweet: "Laps and more laps. This is the 80th time that @carlosainz crosses start/finish line. More to come, this is testing!"
Century on the board for Kimi
Kimi Raikkonen's race-simulation work for Ferrari has made him the first driver to stampede into three-figure territory.
He's on 106 laps and still the figure is climbing. With two and a half hours left in the day that Ferrari could truly clock up some serious mileage today.
The Force India of Nico Hukenberg is also about to bring up lap number 100.
Race-sim work for Kimi
Andrew Benson
Chief F1 writer
"Ferrari's Kimi Raikkonen appears to be on a race-simulation run this afternoon. It will be fascinating later to compare his times with those of Hamilton and the two Red Bull drivers last week."
Oh all right, one more from the archive
Damiano has been in touch using #bbcf1 and points out that there may be pictures to rival the earlier one of Graham and Damon Hill. The below example being one of them.
He's probably right.
Reading left to right, we have Bruce McLaren (100 grands prix, four wins), Stirling Moss (66 grands prix, 16 wins), Tony Brooks (38 grands prix, six wins), Graham Hill (two titles, 176 grands prix, 14 wins), Jo Bonnier (104 grands prix, one win) and Wolfgang von Trips (27 grands prix, two wins), with young Damon (one title, 115 races, 22 wins) at centre, on 17 July 1961.
That's three world titles, 511 races and 65 wins right there, folks. #calculator
Tragically, Ferrari driver Von Trips would die less than two months after this photograph was taken, killed in an accident at Monza while leading the championship. His team-mate Phil Hill went on to take the title, with Von Trips a posthumous runner-up by one point.
F1 journalist Dan Knutson in Barcelona
"Williams technical boss Pat Symonds talked with the media this afternoon. He is pleased with the progress that Williams has made in winter testing.
"He said: 'So far it has gone quite smoothly. As the testing restrictions get harder and harder you have to become more and more disciplined in the way you test. You have just 12 days to cover all the reliability, all the systems, and start looking at performance. Thus far it has gone absolutely on plan - we have not had to change anything. We have got through all the work we planned to do by this stage. We have not spent a lot of time chasing performance in the car. In fact in the first two tests, absolutely nothing in the performance way. At this final test we are now just starting to exercise it a little bit and see what we can get out of it. It looks reasonably promising at the moment. There is still a way to go.'
Get involved - #bbcf1
Henry Evans: "So merc are still in a league of their own... BUT can't wait for the battle behind! Ricciardo vs Vettel vs Bottas = Tasty."
Michael Powell: "V impressive reliability from Force India after only starting to run 2015 car yesterday. Dark horses for a good points haul in Aus?"
David Boyle: "Towards the end of tomorrow's testing, McLaren to turn the Honda engine up to full capacity and set the fastest lap."
Peter Smith: "I've always supported McLaren and look forward to the new Honda partnership, but that Force India looks amazingly improved, well done."
Heath Brett: "Shame the Mercs look so far ahead again, and I can't see any epic battles between Rosberg & Hamilton to liven things ZZzzzz!!!!"
F1 journalist Dan Knutson in Barcelona
"Christian Horner has headed off on a motor scooter. He's no doubt going out around the circuit to see how the Red Bull RB11 goes through the corners."
Still no sign of Mercedes and Hamilton
Mercedes reported in the hour before lunch that they would be making some "experimental set-up changes" before hitting the track again.
Well, whatever that experiment is it's still ongoing.
They've now lost 90 minutes of track time to it and Lewis Hamilton remains mired on just 36 laps for the day. For comparison, Kimi Raikkonen has put up 78 laps and counting for Ferrari.
Like father, like son
Just returning briefly to Graham Hill and Damon Hill.
There is of course only one picture that truly epitomises the only father and son to each become F1 world champion, and it's this cracker from 1964.
And maybe trouble for Lotus too?
Ben Edwards
BBC F1 commentator
"Some puffs of what looks like oil smoke from back of Lotus on this lap."
Problems at McLaren?
Ben Edwards
BBC F1 commentator
"I'm just in front of the McLaren garage. Magnussen was due to come in and go straight out (they moved me out of way) but then he stopped just before the box, they had to wheel it back in and fluid had leaked onto ground which they're now cleaning up. Looked more like coolant than oil but not sure."
"Also just beginning to see some clouds forming overhead after a beautifully clear morning."
Dress bantz from Williams
Williams tweets: "Pat confirms the #FW37 is white and blue not #blackandblue or #whiteandgold although it has got some red #bandwagon"
Massa and Kimi settle in for longer runs
It's been a slow-burner since the restart.
Felipe Massa is doing a long run on the hard tyre for Williams, while Kimi Raikkonen is also going long for Ferrari on the medium.
Kevin Magnussen in the McLaren briefly joined them but came straight back into the pits.
F1 journalist Dan Knutson in Barcelona
"Romain Grosjean talked with the media during the lunch break. The 2015 Lotus is a much better car than last year's E22. 'You can push it hard trying to find the limit,' he said."
Who, what, where, when? Bonus round answer
This one didn't fool too many either.
Graham Hill, the world champion of 1962 and 1968, sits astride his motorbike as he chats with son Damon, who would become champion himself in 1996.
Dan Brown was among those to get in touch with the right answer. He also correctly said the pic was taken in 1975 AND that the bike is a Bultaco Alpina (I'll take your word on that one).
Green flag flies
Lunchtime is over kids. Back to it.
Felipe Massa, quickest this morning, bounds straight onto the track like an eager puppy.
Magnussen settling in
Honda tweet: "With each session, @KevinMagnussen is getting faster, and more comfortable with the #MP430."
Who, what, where, when? Bonus round
Right, this one is slightly different as it's away from the track and there's no cars.
However, there are two F1 world champions in the picture here. Can you tell me who they are? The year's not needed, but I'm open to being impressed.
#bbcf1 please.
Who, what, where, when? The answer
Thanks for playing along. I think that caught quite a few out but I'd say around 70% of you still got it right. Impressive.
The answer was Williams' Thierry Boutsen winning the Australian Grand Prix in the rain, 1989. Craig Wilson was quickest with the right answer.
As it's Saturday I'll do one more.
Two mins...
Force India continue to make up for lost time
Force India tweet: "End of the morning session. Nico was the busiest driver so far, with 76 laps, just one short of yesterday's total."
Who, what, where, when?
Ok, here we go. I was soundly put in my place yesterday for underestimating the depth of the F1 knowledge out there, so I'm going for a bit of a random one today (cue another 99% success rate).
So, tell me who this driver is, who he's driving for, what is going on, and at which track and in which year.
Answer using #bbcf1 please.
Go.
Morning test times, day three
1. Felipe Massa (Williams) 1:23.262 (45 laps)
2. Kimi Raikkonen (Ferrari) 1:23.276 (51)
3. Marcus Ericsson (Sauber) 1:24.477 (50)
4. Nico Hulkenberg (Force India) 1:24.939 (76)
5. Kevin Magnussen (McLaren) 1:25.225 (38)
6. Lewis Hamilton (Mercedes) 1:25.471 (36)
7. Daniel Ricciardo (Red Bull) 1:25.742 (60)
8. Carlos Sainz (Toro Rosso) 1:26.330 (53)
9. Romain Grosjean (Lotus) 1:27.950 (44)
Morning round-up
Andrew Benson
Chief F1 writer
"Well, that was a properly fascinating morning of testing. Felipe Massa and Kimi Raikkonen have grabbed the headlines, but there is no mistaking the overall message that Mercedes appear to have a sizeable advantage.
"Meanwhile, in the context of their winter struggles, it was another encouraging morning for McLaren, with Kevin Magnussen doing 34 laps to add to the 101 Jenson Button managed on Friday, and with no apparent problems. Have Honda finally nailed the reliability of that engine?
"Pace-wise, though, it's not looking great for McLaren at the moment. A 1:25.225 on the softs is pretty slow - 2.5secs off a Mercedes and 1.3secs off a Williams - unless Magnussen did that time on a lot of fuel. But Magnussen would have to had 60kg of fuel in the car - unlikely on a short run - to make that competitive with a Mercedes.
"For McLaren's sake, let's hope the engine is still turned down at this stage."
Chequered flag
Lunchtime. We're done for the morning here in Barcelona.
Times coming up.
Ericsson and Hulkenberg improve on super-softs
The Sauber of Marcus Ericsson displaces goes third with a lap of 1:24.477 on the super-soft.
Force India's Nico Hulkenberg also has the red-walled tyre on and goes fourth with a 1:24.939.
Quiz time approaching
Just to mark your cards for some upcoming lunchtime buffoonery. I'll do my usual thing of blurring famous moments in F1 history and you have to tell me who is in said picture, as well as when and where it was taken.
Top three as lunch looms
1. Felipe Massa (Williams) 1:23.262 (set on super-soft tyre)
2. Kimi Raikkonen (Ferrari) 1:23.276 (super-soft)
3. Kevin Magnussen (McLaren) 1:25.225 (soft)
Super-soft times hint at scale of Merc advantage
Andrew Benson
Chief F1 writer
"These recent fast times set by Felipe Massa in the Williams and Kimi Raikkonen's Ferrari fit exactly the pattern that has emerged over the last few days. Both setting a 1:22.3 on super-softs, they are still 0.5secs short of the time set on soft tyres by Nico Rosberg's Mercedes on Friday - and the softs are at least that margin slower than the super-softs.
"There is more and more evidence that the Mercedes has an advantage of about a second over the other teams and that Williams, Ferrari and Red Bull are exceptionally closely matched behind, even if we are yet to see a qualifying-type lap from the Red Bull this week."
McLaren bares its teeth
Kevin Magnussen has hauled the McLaren up to third place in among this pre-lunchtime frenzy. A 1:25.225 on the soft tyre is the team's best effort of the week, eclipsing Jenson Button's 1:25.590 yesterday.
Raikkonen breathing down Massa's neck
Ferrari's Kimi Raikkonen has joined Felipe Massa in the hooning joys of a set of super-softs and lobs in a 1:23.276, just 0.014secs off the Williams man.
F1 journalist Dan Knutson in Barcelona
"The Ferrari mechanics run hither and thither with the screens trying to hide the car when Kimi Raikkonen brings the car into the pits. There must be some new parts on it today."
Massa raises the bar once more
Felipe Massa's Williams is now sporting a set of super-soft tyres and his lap times are duly falling - he's just done a 1m23.262s. That's still half a second off Nico Rosberg's time on the softs for Mercedes yesterday.
Get involved
As always we need your observations on today's testing action. Send us your comments using #bbcf1.
Change at the top
Felipe Massa, who has the second fastest time of the Barcelona tests so far, jumps to the top of the order today with a 1:24.950 in the Williams FW37. That's a medium-tyre run, and is some 1.5secs down on his best time of the test, which came on the faster soft tyre.
Quarter of a century for Magnussen
McLaren on Twitter: "The track's warming up and there's blue skies overhead. 25 laps on the board for Kev."
The Hulk goes third
Still the Force India powers on. I don't think it's had a single glitch since it came out the wrappers yesterday.
Nico Hulkenberg is now up to third place after a 1:26.137 on the soft tyre.
F1 journalist Dan Knutson in Barcelona
"McLaren is running the Melbourne-spec Honda engine today, according to sources."
It is understood the Honda engine has been running at a limited capacity in testing so far, so this may indicate the unit is at 100% power today. Of course, only McLaren and Honda know the truth!
Sainz sets a time
It looks like pit stop practice is over at Toro Rosso.
Carlos Sainz goes out and puts up a 1:27.823 on the medium tyre, good for seventh place.
All the drivers have now posted a lap time.
Getting wired down at Williams
Lee McKenzie
BBC F1 pit-lane reporter
"Lovely catch up with Massa and Bottas at Williams. Good atmosphere in the team. Great coffee too. Feeling a little more awake now."
F1 journalist Dan Knutson in Barcelona
"Toro Rosso and Carlos Sainz are doing pit stop practice. It's an important element of pre-season testing. Jenson Button said yesterday: 'We did pit stop practice and we did practice starts. We have not done a lot of that in winter testing. So those sorts of things you need to work on as well, not just the performance of the car.'"
Force India on the move
We've been bigging up the promise of the new Force India after its showing on debut yesterday, and now the speed is starting to show through.
Nico Hulkenberg has pinged the VJM08 into fifth place with a 1:27.404, within two seconds of the pace-setting Mercedes on the same tyre.
Magnussen on the board
McLaren's Kevin Magnussen has finally clocked a time, a 1:29.336 on the medium Pirelli. The Dane, who lost his drive this season to Fernando Alonso, is up to 12 laps.
That leaves Toro Rosso's Carlos Sainz as the last man still to set a time, although he has done 18 installation laps.
Two hours gone
Here's your top three check:
1. Lewis Hamilton (Mercedes) 1:25.471 (30 laps)
2. Daniel Ricciardo (Red Bull) 1:25.941 (27)
3. Kimi Raikkonen (Ferrari) 1:26.532 (22)
Hamilton goes faster
Lewis Hamilton sets a new fastest lap of the day for Mercedes. On the medium tyre he posts a 1:25.471.
New Force India powers on
Force India tweet: "Flying visit to the pits for Nico and the VJM08. A few quick adjustments and we're on our way again."
Nico Hulkenberg has done 37 laps today with a best time of 1:29.277.
It's all gravy (train)
Lotus tweet: "Nose change for @RGrosjean - all part of the aero evaluation gravy train."
Day two times recap
It's probably worth you having yesterday's times to hand. Y'know, for reference.
At the moment the best times today are some three and a half second off Rosberg's howitzer yesterday, so plenty of scope for improvement.
1. Nico Rosberg (Mercedes) 1:22.792 (106 laps)
2. Valtteri Bottas (Williams) 1:23.995 (90)
3. Felipe Nasr (Sauber) 1:24.071 (141)
4. Sebastian Vettel (Ferrari) 1:25.339 (143)
5. Jenson Button (McLaren) 1:25.590 (101)
6. Pastor Maldonado (Lotus) 1:26.705 (140)
7. Max Verstappen (Toro Rosso) 1:26.766 (139)
8. Daniil Kvyat (Red Bull) 1:26.965 (84)
9. Nico Hulkenberg (Force India) 1:28.412 (77)
35 million cans of Red Bull
No, that's not the answer to the question, "what does it take to survive nine hours of blogging on F1 testing?"
It is in fact the distance Toro Rosso have gone in testing, as this tweet explains: "As @carlosainz completes lap 10 of day, it's 1000 laps in testing: 4573kms, nearly 35 Million @redbull cans in a row!"
F1 journalist Dan Knutson in Barcelona
"There are only two more days of the permitted 12 preseason testing days to go. What a difference to years gone by when there were no limits on testing and the big teams would test for days on end."
One hour gone
Right, the lads have been out there for 60 whole minutes now. Here's the top three as it stands.
1. Lewis Hamilton (Mercedes) 1:26.110 (20 laps)
2. Kimi Raikkonen (Ferrari) 1:26.532 (19)
3. Felipe Massa (Williams) 1:27.271 (12)
Magnussen hits the track
Just as we were starting to wring our hands over McLaren, Kevin Magnussen noses the MP4-30 out of the garage to complete an installation lap.
Button reflects on encouraging century
Andrew Benson
Chief F1 writer
"Finally, McLaren have done some miles. In one day on Friday, Jenson Button managed 100 laps - that is pretty much exactly half the entire total of their previous running throughout nine previous days of testing.
"McLaren are still way behind their key rivals in terms of understanding their car - Mercedes have been doing that sort of mileage every day - but as Button said: 'It's a starting point.'
"He added: 'It's a shame we've missed so many days, but were on the right track now and it's definitely progress. We have a lot of work to do still. We know we're not the quickest guys out there. We have a lot of work to do with set-up and getting the maximum out of the power unit, but you'll see a lot of improvements out of us before Melbourne.'"
Mileage mounts up
Some of these guys aren't hanging around today. The times are nothing special but the miles are already mounting up.
With just over half an hour gone, Kimi Raikkonen's Ferrari has done 16 laps, the Force India of Nico Hulkenberg 14, Lewis Hamiton's Mercedes is on 15 and the Red Bull of Daniel Ricciardo 10.
The only car not to set a lap is that of McLaren's Kevin Magnussen. After completing 100 laps with Jenson Button at the wheel yesterday, let's hope this is not a sign of fresh problems for the team.
Force India impress on first outing
Andrew Benson
Chief F1 writer
"Force India had to wait until three days before the end of testing to run their new car, its build delayed by cash-flow problems. But at least when it ran, it did so flawlessly, Nico Hulkenberg completing 77 laps in one afternoon.
"As the driver himself said: 'That is quite remarkable.' Performance-wise it was nothing to write home about, but first days are always about box-ticking. There were a lot of baseline checks today and getting a feel for the car.'
"The German has another go on Saturday before handing over to team-mate Sergio Perez for the final day on Sunday."
Ericsson on track
Sauber on Twitter: "Marcus is going out for the installation lap."
Hamilton ready to go
Mercedes on Twitter: This fella is ready to rock, that's for sure! Good morning @LewisHamilton - let's do this!"
Bottas surprised by 'very quick' Mercedes
Andrew Benson
Chief F1 writer
"You didn't have to be a psychologist to realise from the tone in Williams driver Valtteri Bottas's voice that seeing Nico Rosberg's pace had been a dispiriting experience. 'It's pretty quick,' the Finn said. 'I think everyone was a little bit surprised. Everyone knew they were quick. But they are very quick. But that's how it is.'
"So much was revealed in those few words. Regardless of the fuel load Rosberg was on, we now know Bottas must have been pretty low on fuel - otherwise he would not have been so concerned about the Mercedes' pace.
"So now there is more or less a benchmark for a Williams performance, and from that much more can be extrapolated. But the key thing seems clear. Mercedes are, again, miles ahead."
First time on the board
It's been a predictably steady start to the day with temperatures so low.
The Williams of Felipe Massa sets the early benchmark, a 1:27.271 on the soft compound.
Today's drivers
In no particular order, we have Romain Grosjean (Lotus), Marcus Ericsson (Sauber), Lewis Hamilton (Mercedes), Daniel Ricciardo (Red Bull), Kimi Raikkonen (Ferrari), Felipe Massa (Williams), Nico Hulkenberg (Force India), Carlos Sainz (Toro Rosso), Kevin Magnussen (McLaren).
Mercedes 'looks nailed to the track'
Ben Edwards
BBC F1 commentator
"I was watching the cars out on track for a time on Friday. The Mercedes looks nailed to the track, with brilliant turn-in to the corners. It's no surprise they have been looking so fast.
"Of the rest, I'd say the Williams probably looks second best, while the Ferrari also looks reasonably good. The drivers can get on the power reasonably early, which is a good sign for the Italian team as traction has been one of their problems in recent years, but the turn-in is still not as sharp or decisive as they might want.
"The McLaren looks OK, too - although we know they were running down on power. Unfortunately, the Red Bull did not do many laps while I was out there."
Chilly morning in Barcelona
There was a frost on the ground around the Circuit de Catalunya today, and F1 journalist Dan Knutson in Barcelona informs us it is indeed a bracing morning.
"Clear blue skies with an air temperature of 3.4 degrees Centigrade and a temperature of 13.9 degrees Centigrade. There is a zero percent chance of rain today," he says.
Green flag
Let's go testing.
Mercedes set to dominate again
Andrew Benson
Chief F1 writer
"If there were any doubts about who was leading the way ahead of the new Formula 1 season - and among the teams and drivers there were not really - they were finally expunged on Friday.
"Nico Rosberg set a new fastest time of the winter, on the first outing for Mercedes on the soft tyre. He was quickest by 1.2 seconds on the day, from Williams's Valtteri Bottas, and by 0.7secs over the previous fastest time, set by Williams's Felipe Massa. That compares with the 0.8secs advantage Lewis Hamilton had on a race simulation run at the last test over the Red Bull and Williams.
"One leading team boss told BBC Sport he thought Mercedes had a one-second margin over the rest earlier this week.
"Everyone ready for Hamilton v Rosberg part II?"
Good morning
Welcome to the penultimate day of pre-season F1 testing for 2015.
Nico Rosberg rather let the cat out of the bag yesterday as Mercedes' searing pace was shown up with a quite brilliant lap on the soft Pirelli tyre.
Can the other teams respond? Well, we should find out over the next few hours.