F1 Bahrain pre-season testing live commentary and updates - day 4

Nobody is chomping at the bit to get out as soon as the session goes green, so we've got a gentle start to the afternoon.

Bearman has put an end to the silence by heading out for his first run of the day for Haas having taken over from Ocon.

Lawson, who has taken over from Lindblad, has also headed out for his first run down at Racing Bulls, while at Mercedes Russell is race suited and booted waiting to hop into the W17.

Fresh from the FIA press conference, Hamilton has jumped into the Ferrari for the first time in this test to get his first experience of his upgraded SF-26. He is running with a lot of flow-vis paint all over the rear wing and diffuser of the car, just as Leclerc did this morning.

Plenty of double driver duty today, with Piastri fresh into action for McLaren and moments later is joined by Russell in the Mercedes. In fact, the only team who didn't 100% confirm both drivers would be running today was Aston Martin, who only stated Alonso in the car for the morning session. So, we could get a full 22 today if Stroll takes over.

And a quick look to Aston Martin's communications points out Stroll will be in action later today... That's the full set then. Still no sign of the Canadian driver as the team continues to attend to the car after its earlier power unit issue.

Also no sign of Verstappen in the Red Bull yet either, after the team's pressure problem with one of the coolant circuits in the engine from this morning.

In this short lull, we'll pick up a few questions that have come in. 

'Victor N' asks: "Apparently you can identify the Audi (fuel smell) with your face turned away from the track. Any confirmation for this from Autosport trackside?"

That is exactly what Jake Boxall-Legge reported during the first test in Bahrain, saying you can smell the Audi coming with the cars detectable using the new sustainable fuels.

Hadjar has return to action the Red Bull, rather than Verstappen, so given his lost track time we can presume the team has shuffled its plan for today. The French driver also lost half a day in the last test due to a mechanical issue so he's down on laps vs his team-mate. Elsewhere Colapinto is in at Alpine and Sainz is in at Williams.

Russell has reported a heavier steering feel compared to what he felt in the Mercedes last week.

Nobody is troubling the top lap times at the moment, as Russell goes 14th for the day with a 1m38.291s set on the C1 hard tyres.

Down at Aston Martin, Stroll is in the car and heads out for the first time today.

Russell locks up his front-right tyre into Turn 4 with those C1 tyres, as he appears to be on a race stint on high fuel. Just moments before that Sainz locked up at Turn 1 in a similar incident.

With the Aston Martin back on the track we've been given a good look at the car and it is running with an eye-catching high rake angle. Newey's cars pre-ground effect era always ran with an aggressive rake, but compared to other cars at this test it looks so different. Is different better?

Fernando Alonso, Aston Martin Racing

Photo by: Simon Galloway / LAT Images via Getty Images

A couple more lock ups to report: Stroll into Turn 1 followed by Hamilton also at Turn 1. They look like classic cases of cold tyres failing to bite under heavy braking.

Meanwhile, Bortoleto is on track for Audi so the only drivers missing from today's action is Verstappen and Bottas.

Anthony Davidson on TV commentary suspects a gearbox-related issue, as a slow-mo replay shows that as he went down the gears he lost drive. For the first time ever the team is manufacturing its own gearbox as part of its new collaboration with Honda.

Well, we're getting closer to that Melbourne opener with increased track time by the day. So I'd say this is a good time for you to get your predictions in for the 2026 season - go wild... 

Obviously lap time isn't the priority at this stage, as it is mileage instead. So here's the count for the afternoon so far:

Russell - 18

Hamilton - 18

Piastri - 14

Colapinto - 10

Hadjar - 9

Lawson - 18

Sainz - 14

Stroll - 7

Bortoleto - 6

Bearman - 17

Over the lunch break we had a press conference with four drivers, one of which was Hamilton. Here's what he had to say on the new start procedure for 2026, after McLaren boss Andrea Stella called for "imperative" safety tweaks...

Lewis Hamilton, Ferrari, Max Verstappen, Red Bull Racing, Fernando Alonso, Aston Martin Racing, Gabriel Bortoleto, Audi F1 Team, Valtteri Bottas, Cadillac Racing

Photo by: Sam Bagnall / Sutton Images via Getty Images

Sainz has just set his best laptime with a 1m35.378s, which is good enough for seventh. The problem? Not only is it 1.639s off leader Leclerc, but it's close to a second behind Russell in sixth.

The gap between the front runners and midfield looks to have increased this year, Esteban Ocon previously claiming they're "seconds away". 

Our man Jake Boxall-Legge even offered a vague prediction of the 2026 pecking order at the end of last week's testing. 

Stroll's car has now returned to his garage, so Aston Martin can get to work on discovering yet another problem with its AMR26...

Lance Stroll, Aston Martin Racing

Photo by: Zak Mauger / LAT Images via Getty Images

As we all know by now, Verstappen caused a huge stir last week when he labelled the new F1 regs as "anti-racing" and like "Formula E on steroids". He then doubled down on those comments in today's press conference, before his boss Laurent Mekies was asked about the matter during the team principal session.

On track, it's a rather quiet session at the moment with only Hamilton and Bortoleto currently running. Hamilton is using prototype tyres with mediums for the Audi.

So what are your thoughts on that? Harsh on Mercedes or should zero loopholes be allowed in the regulations?

It comes after the compression ratio was reduced from 18:1 to 16:1, but according to Article C.5.4.3, a static test at ambient temperature is the only method of measuring the ratio.

So Mercedes had found a way to increase its compression ratio while the engine is running, before having it at 16:1 once at ambient temp. 

May I refer you to yesterday's article, where Alpine managing director Steve Nielsen, whose team is a Mercedes customer, revealed his worries for what kind of precedent this backlash sets. 

“If we're saying that a very clear set of regulations, written set of regulations can be challenged in this way, then what else is off limits?

“Everything's up for discussion then. If a certain set of teams don't like something that's very clearly written, if suddenly you can have a lobby group and change it, then you're in a whole different world.

“People invest an awful lot of time and money, and particularly money into this, in good faith, and if suddenly we're going into a world where everything can be challenged, even though it's clearly written for any reasons other than safety reasons, then I think that's a whole new world, which we've not been in before.

“So I think the compression ratio discussion is one thing, but I think it's very clear. You could say I'm biased because we've got a Mercedes engine in our car, but that's honestly what I believe.

“But I think the more fundamental question is, do we really want a sport where clearly written stuff can just be challenged because people fancy doing it? I think that's for the FIA to answer…”

Steve Nielsen, Managing Director at Alpine F1

Photo by: Mark Sutton / Formula 1 via Getty Images

Back to the track and it's still not massively busy with only Piastri, Russell, Sainz and Bortoleto in their cars. Doesn't look like any are threatening Piastri's benchmark for now. 

It's not been a great day so far for Cadillac. It only completed 24 laps this morning with Perez as various sensor issues limited his running. 

This afternoon, Bottas has only done 11 tours and wasn't seen on track until the second half of the session. We're still trying to find out why Bottas' running has been so limited. 

Sergio Perez, Cadillac Racing

Photo by: Kym Illman / Getty Images

As ever, please do continue to submit your questions as we approach the final 90 minutes of this session...anything you want from the world of F1!