Fernando Alonso stops on track but later goes second quickest, behind Ferrari's Kimi Raikkonen
Sebastian Vettel set the fastest lap recorded at this circuit (1:17.182) on Thursday
Final day of Formula 1 testing
Session runs until 17:00 GMT
Get involved: What have we learned from testing? #bbcf1
Kevin Magnussen hopes Haas do better than last year when they failed to score points in nine races, including three of the last four of the season.
But the signs are that they will be more competitive today. Romain Grosjean has done 39 laps today (only Brendon Hartley in his Toro Rosso has done more with 40) and Grosjean is fourth quickest.
Andrew Benson
BBC Sport’s chief F1 writer
Kevin Magnussen set the second fastest time on Thursday and he did it in super-soft tyres - two grades harder in the confusing nomenclature this year than the hyper-softs most used. It opened a few eyes up and down the pit lane - and may well cause a bit of controversy in the end, with murmurings starting about the closeness of Haas’ relationship with Ferrari and how closely the car resembles last year’s Maranello challenger.
That, though, is well off Magnussen’s radar. And he was keeping expectations under control. “We have to wait and see,” he said. “We don’t know what other people can do, or if other people have a lot of fuel in the car. So we are not getting excited already. We feel like we have improved our car, and we definitely have improved our car, but so has everyone else.
"So we will have to wait until Melbourne to really get a better idea of where we are going to be, and then the first couple of race will probably show another picture. Hopefully we can do well, but it is too early to say now. I feel like we have made a better car than last year and we have a goal to improve on last year. We are on course to do that.”
Image source, Getty ImagesThe times are being shaved. Lewis Hamilton beats his best time with a 1:19.464 on the super-softs, before Ferrari's Kimi Raikkonen goes quicker with a 1:18.298, also on the super-softs.
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More problems for Fernando Alonso and McLaren
Chris (is better than his brother Sam) Marsh: We all know Alonso can get more out of his car than possibly anyone else on the grid, but given the direction towards engine/parts management F1 has taken is he now out of his depth? I unfortunately think so.
Reece Young: Starting to think it is McLaren's insistence on a tight rear end that is causing issues. The Renault engine looks solid in all other cars. And the Honda engine is looking tremendous in the Toro Rosso.
James: Still trying to understand why everyone was so optimistic for McLaren. Do we not feel the issue is Alonso maybe? He is always having issues...Vandoorne less so.
Dean McNamara: How can Vandoorne do 151 laps without incident and then soon as Alonso steps into the McLaren it all goes pear shaped?
We have been held up by Charles Leclerc, who got too friendly with a barrier. Luckily, he is OK, writing on Twitter and hoping to get back out there soon.
He says: "Very happy about the pace, but pushed too much, spun and touched the wall a little bit.
"Stupid to do that at this time of the day, I will learn from it. Hopefully back on track soon."
BBC Sport app users may need to click on the link to see the tweet.
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And we're back. Hamilton, Ocon Grosjean, Hartley and Ricciardo get back out there.
Dan Knutson
F1 journalist in Barcelona
McLaren certainly did not want to start the final day of pre-season testing with yet another trip on the truck.
Image source, Dan KnutsonNo action at the moment as the track officials deal with Charles Leclerc's Sauber that went into the barrier.
Here are the times so far today...
No times set from Fernando Alonso (McLaren, seven laps) or Carlos Sainz (Renault, four laps).
Image source, Getty ImagesMore problems for Fernando Alonso and McLaren
Reece Young: The McLaren breaks down as the Toro Rosso continues piling on the laps with the "GP2" Honda engine. Alonso is a great driver, one of the best, but he can't make career decisions.
Batch_STFC: They still have a far far greater chance of being podium competative this season. But testing to state the obvious... Not ideal..
Edward Drogeham: Fernando Alonso stopped the car on the track. "It looks like some sort of fluid got out of the car". Yeah, it's blood, sweat and tears...!
Fantasy-f1-league: Was the fluid out of the McLaren Alonso's tears?
A crash involving Charles Leclerc in his Sauber has brought out the red flags again.
A tweet from the Circuit de Barcelona-Catalunya says Leclerc is "OK".
BBC Sport app users may need to click on the link to see the tweet.
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Drama on the track for McLaren, but now we have a new fastest man of the day. It had been Romain Grosjean of Haas, very briefly it was Kimi Raikkonen in his Ferrari, but now it is Lewis Hamilton, who has set the benchmark of 1:19.601.
As a comparison, Sebastian Vettel's time yesterday was 1:17.182 on the hyper-softs, with Hamilton's mark coming on the super-softs.
#bbcf1
Joanna Harran: First check in with yourselves of the day and the first thing I see is ‘Alonso stopped’. Noooooo. Hope it is just a blip.
LSJ: Could we perhaps not change the Red Flags to Papaya Orange? I feel bad for Alonso.
Rob: I'm starting to think that maybe McLaren aren't the problem. Maybe it's Alonso... Still my favourite driver though. #cursed, external
Mark Tyler: I've been a McLaren fan since I was 10 years old I'm now 34. I don't think I have another season of disappointment in me! What GT series is @JensonButton, external racing in again? I'm off.
Come back. Mark! Mark! MARK!
Image source, Getty ImagesAlonso's McLaren has been removed from the track. He has done seven laps, but not set a time. The green flags have been waved, and we are back under way, with most drivers quickly returning to the track.
Work for McLaren to do though before Alonso can get back out there.
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Dan Knutson
F1 journalist in Barcelona
The marshals are putting down “oil dry” on parts of the track leading to Turn 7 where Fernando Alonso’s McLaren stopped. So it looks like some sort of fluid got out of the car.
This is what appeared on our website only two days ago...
McLaren's Fernando Alonso insists there is "nothing fundamentally wrong on the car" after the team suffered more problems in testing.
Alonso was delayed for nearly seven hours after his car broke down because of an oil leak on Wednesday.
"The issues we had are well under control," said Alonso. It was the latest in a series of reliability problems for the team.
Alonso managed less than a third of the laps done during the day by Ricciardo and the Mercedes and Renault drivers.
Today, he has come to a halt on the track again.
Another day, another problem for McLaren. Fernando Alonso has come to a halt at turn seven.
Another frustrating day in store for the Spaniard.
Red flag. All back to the garages.
Andrew Benson
BBC Sport’s chief F1 writer
For this final day of testing, Mercedes are sticking with their split driver programme, one in the morning and another in the afternoon.
Lewis Hamilton says it is working well. “In doing full days, yeah I can do it, but for one it’s boring,” he said. “Ultimately for me - and I’m sure it’s the same for people that are in the team but particularly for a driver - we’re not robots, firstly. If you’re just pounding around doing the same thing over and over again you lose interest and your feedback for sure can deteriorate because your interest declines.
"So on the positive side if you get a good day you both get to drive on that good day and the next day could be wet. So that works well. And then on the same day you get two sets of feedback in pretty much the same conditions, so that’s double the feedback that you get back. We feel fresh in terms of your approach.
"Half a day is not really that physically challenging to have done half a day but I feel excited to drive in the morning. It’s going to be hotter. And at the end of that morning or afternoon run you don’t feel mentally destroyed that you can’t be bothered. I think it just keeps you fresh and I praise the team for allowing us to do that approach because we’ve lost nothing. You’ve seen we’ve won championships in the last years and we have done this for a long time. It works.”
Image source, Getty ImagesAt 08:45 GMT...
Image source, Getty ImagesRomain Grosjean jumps to the top of the times with a lap of 1:20.351 on the softs.
We're still three seconds off Vettel's best time yesterday, but still some early encouragement for Haas.
A good day yesterday for Toro Rosso and today has not been too bad for them so far either.
Brendon Hartley, on the softs is the third quickest... but we have a new fastest man.