Ferrari's Leclerc fastest on final day of pre-season testing in Bahrain
McLaren's Norris in second, with Red Bull's Verstappen third
Aston Martin finished testing early after completing only six laps on last day
First race in Melbourne takes place from 6-8 March
New technical regulations biggest change in F1 for years
It's sunny and blue skies as it has been all week in Bahrain and the drivers will be managing their new cars in these hot conditions.
Air temperature is currently 26 degrees and the track temperature is 45 degrees.
The track conditions during the four-hour afternoon session are more representative to race conditions.
It won't be long until the drivers will be back at this track, with the Grand Prix weekend on 10-12 April.
Oscar Piastri (McLaren) - 49
Kimi Antonelli (Mercedes) - 49
Isack Hadjar (Red Bull) - 38
Charles Leclerc (Ferrari) - 64
Carlos Sainz (Williams) - 48
Arvid Lindblad (Racing Bulls) - 57
Lance Stroll (Aston Martin) - 0
Pierre Gasly (Alpine) - 38
Esteban Ocon (Haas) - 50
Nico Hulkenberg (Audi) - 49
Sergio Perez (Cadillac) - 29
Select the 'Get Involved' button to have your say
Tim, London: I think we could see a 2010 style season where its Ferrari vs Mercedes vs Red Bull. This time Ferrari will win.
Anees, Sheffield: At every team Adrian Newey has always had great engineers and designers around him. At Aston Martin he doesn't really have that there will still be a lot of recruiting to do for the team to be built how he wants it for them to be successful
Ollie, Billericay: Cadillac seem to be struggling quite a bit getting laps in. Will certainly cause some issues in the first races I can imagine... Is the car good enough for consistent points too or is it going to be a very rough season for them?
Andrew Benson
BBC F1 correspondent in Bahrain
Image source, Getty ImagesLando Norris has admitted he described the new Formula 1 cars as "a lot of fun" last week to "see what the reaction was of everyone".
The world champion also suggested Max Verstappen, who had said the cars were "just not F1", could "go and find something else to do" if he did not like them.
On Thursday, at the second pre-season test, Norris said: "I just didn't want to come out into the media and complain to everyone on the first weekend back.
"I just wanted to say that and see what the reaction was of everyone.
"It's been quite an amusing week, and it certainly made a lot of people comment and say a lot of things."
Oscar Piastri has been released from the McLaren garage and has been adding to his tally of 44 laps.
The Australian is third-fastest and is 0.663 from Charles Leclerc, who is top of the times in his Ferrari and has been for the majority of this session.
Piastri's team-mate and reigning world champion Lando Norris has been speaking to the media about the new cars.
Image source, Getty ImagesThere are five manufacturers providing power units for the new era of regulations from 2026 and beyond, with newcomers Audi jumping straight in at the deep end and developing their own engine.
If you're just joining us and wondering where Aston Martin are... well, Honda, the power unit for Aston Martin, released a statement earlier explaining.
"Our last run with Fernando Alonso yesterday showed a battery-related issue that impacted our test plan with Aston Martin," the statement said.
"Due to this and a shortage of power unit parts, we have adapted today's run plan to be very limited and consist only of short stints."
Canadian Lance Stroll is the man in the cockpit for the final day of testing, but has not yet made an appearance on track yet.
Image source, Getty ImagesThere seems to be a bit of a theme running down at Cadillac with their drivers not getting as many laps completed as their rivals.
Mexican Sergio Perez is taking the morning session and has completed 16 laps so far.
However, they are the new team in town and it's still early days. They are also the first start-up entry since Haas in 2016.
Image source, Getty ImagesMcLaren's Oscar Piastri has remained in the garage and the mechanics look like they are working on the rear of his car.
Charles Leclerc is looking comfortable and has completed the most laps of the session so far with 50 laps in his Ferrari.
It's looking like a more positive day for the Italian team after Lewis Hamilton only managed five laps in his morning session on day two. He made the most of the four-hour afternoon session though and completed 73 laps.
1) Charles Leclerc (Ferrari) - 1:33.689
2) Kimi Antonelli (Mercedes) +0.227
3) Oscar Piastri (McLaren) +0.663
4) Esteban Ocon (Haas) +0.805
5) Isack Hadjar (Red Bull) +0.822
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Ryan, Scotland: Does anyone else have a decent feeling about Ferrari this year? Or is it all a bit premature Really hope to see Lewis enjoy a better time than last year. Could be a really close battle between the top 4 teams
Lee, Surrey: This will be a wasted season for Aston Martin now. By the time Honda sort out the power unit (if they do), any design advantages the car may have will have been copied by the others.
Thomas, London: I think that Oscar Piastri is deffo best
Good news! The Mercedes has now been cleared and drivers are wasting no time to get back on track.
Kimi Antonelli had a quick look at his Mercedes before heading off the track. I wonder what has happened there.
The Italian teenager completed 49 laps so far, but his team-mate George Russell is taking over this afternoon.
The clock will be ticking down in Antonelli's side of the garage to get the car back and fixed in time to do some more running this session.
He's currently second-fastest, 0.227 seconds from Charles Leclerc's time.
Kimi Antonelli didn't manage to get his Mercedes up and running again, so it's a red flag.
He's getting out the car now and will head back to the garage.
Kimi Antonelli has stopped at the side of Turns 10 and 11 in his Mercedes.
As you can see, there is no sign of Lewis Hamilton (Ferrari), Fernando Alonso (Aston Martin), Alex Albon (Williams), Liam Lawson (Racing Bulls) and Franco Colapinto (Alpine) in today's schedule.
This is because they did a full day of testing yesterday to get to grips with the car and this new era of regulations. It's now time for their team-mates to do the same today and make the most of the time on track.
Morning session:
Oscar Piastri (McLaren)
Kimi Antonelli (Mercedes)
Isack Hadjar (Red Bull)
Esteban Ocon (Haas)
Nico Hulkenberg (Audi)
Sergio Perez (Cadillac)
Afternoon session:
Lando Norris (McLaren)
George Russell (Mercedes)
Max Verstappen (Red Bull)
Oliver Bearman (Haas)
Gabriel Bortoleto (Audi)
Valtteri Bottas (Cadillac)
All day:
Charles Leclerc (Ferrari)
Carlos Sainz (Williams)
Arvid Lindblad (Racing Bulls)
Lance Stroll (Aston Martin)
Pierre Gasly (Alpine)
Thanks so much Tas and good morning everyone! We're on the final day of testing before we head to the first race weekend of the season in Australia on 6-8 March. Exciting times!
Charles Leclerc is still top of the times in his Ferrari with a time of 1:33.689.
Let's settle in then for the last two hours of this morning session.
Image source, Getty ImagesTasnim Chowdhury
BBC Sport journalist
Just the four drivers out on track at the moment, Charles Leclerc, Oscar Piastri, Carlos Sainz and Pierre Gasly.
Esteban Ocon has ditched the inters and heads back onto the track.
Right so, my morning testing session is up, so I am going to hand over all responsibilities to Alicia, who will take you through the final two hours of the morning session.
Select the 'Get Involved' button to have your say
Karly, Ayrshire: I think Lando will go back to back. Clearly there is no one faster on the grid. He has nothing to prove and McLaren have such a strong team now.
Martin, Smethwick: Never underestimate Max in the drivers' championship. See how close he got last year. Hopefully we'll see some surprise results because of reliability and deployment issues especially in wet races.
Jon, Dorset: Adrian Newey is a design genius, but he was never going to be an immediate saviour for Aston Martin, given the massive rule changes. Also, you could have the best design on the grid, but unreliable power units will neutralise any advantage, so Honda must resolve this, first and foremost.