We'll keep an eye out for Kimi Raikkonen's thoughts on the head protection system hopefully just after lunch.

After one lap with the halo device, Raikkonen has just gone fastest without it, clocking 1:27.607.

Andrew Benson
Chief F1 writer

Image source, Getty Images

Undoubtedly one of the big stories of this pre-season has been the progress McLaren-Honda have made. Of course it was needed after a dismal 2015, but there is no doubt McLaren - and their engine partner in particular - have made a big step forward. 

Jenson Button says of the deployment of hybrid energy - the engine’s biggest weakness last year - that “the progress is massive in that area”. And Honda have some “massive upgrades during the year”. 

But Button emphasises that “there is a lot more we need to do”. “We are a long way behind Mercedes still,” he added. “The first two or three teams are not for us to think about. The middle of the pack is very competitive. It should be fun at the first race even if we are not achieving our ultimate goals.”

I tell you what I have enjoyed seeing so far in testing, things going well for McLaren. Can't have the talent of Fernando Alonso and Jenson Button being wasted and, reliability issues last Friday aside, they'll be pleased with how things are going so far.

Speaking of Alonso, he gives the smattering of Spanish fans something to cheer as he goes fastest with 1:27.735.

Several times being put down inside the first half hour of testing as Pascal Wehrlein goes fastest with 1:29.126.

Jolyon Palmer (1.29.355), Max Verstappen (1:30.273) and Nico Hulkenberg (1:35.046) have also completed their first flying laps. 

Verstappen and Hulkenberg's times came on the soft tyres, the rest on mediums.

Crikey, I've gone big screen here. Best take extra care with those typos...

Andrew Benson
Chief F1 writer

Lewis Hamilton might have been struggling to get the best out of the car on low fuel and soft tyres on Wednesday, and he may have been some way of Nico Rosberg in terms of best laps in last week’s first test, too. But this week has provided the first chance to compare the cars in race trim. 

Both Mercedes and Red Bull did race simulations on Wednesday with Rosberg and Daniel Ricciardo, and it won’t surprise anyone to hear that Rosberg was on average 0.6secs a lap quicker than the Australian. Hamilton? He did his race sim on the first day of the test, Tuesday. He was on average 0.19secs quicker than Rosberg.

Fresh from snapping Kimi Raikkonen in action, Nico Rosberg climbs into his Mercedes and proceeds to clock the first time of the day - 1:37.147.

As well a testing out the Ferrari, Kimi Raikkonen is also testing the new cockpit head protection that will be introduced next year.

The device, called a 'halo' is designed to guard against impacts from large airborne debris. 

Read more here. 

Best seat in the house right here.

Where are you following testing from? Send in a pic to #bbcf1, external

There's an immediate rumble of engines and first out is Jolyon Palmer for Renault.

Max Verstappen, Kimi Raikkonen, Felipe Nasr and Nico Hulkenberg soon follow suit.

Green flag and away we go. 

For some of the drivers this will be their final run out before the season gets under way for real. 

A big day in prospect.

Andrew Benson
Chief F1 writer

The new Haas team have had a bit of a wake-up call over the last two days, the car barely running because of various engine problems. Team owner Gene Haas was marvelling at the complexity of modern F1 cars. 

"We'll see how it goes down the road, how difficult it is,” said Haas, who is hoping for a better final two days of testing. “I can understand how teams struggle in this business, even the big ones. There are a lot of technical challenges to overcome. It's a case of, can we figure out the organisation such that we can overcome these problems?”

Lewis Hamilton may want to get testing wrapped up early, but Haas probably fancy a few days more.

Esteban Gutierrez managed a solitary install lap yesterday morning before problems hit and he didn't get out again all day. 

Looks like they are good to go today, though.

Mercedes: Nico Rosberg/Lewis Hamilton

Ferrari: Kimi Raikkonen

Williams: Felipe Massa

Red Bull: Daniil Kvyat 

Force India: Nico Hulkenberg

Renault: Jolyon Palmer

Toro Rosso: Max Verstappen

Sauber: Felipe Nasr

McLaren: Fernando Alonso

Manor: Pascal Wehrlein

Haas: Romain Grosjean