F1 Testing: Oscar Piastri's running limited by McLaren technical issue as Aston Martin make first appearance in Barcelona

A technical issue cut short McLaren's running on the penultimate day of Formula 1's first 2026 pre-season testing event as rivals Mercedes and Ferrari delivered strong showings in Barcelona.

Having made their first appearance of the week on Wednesday as reigning world champion Lando Norris debuted the MCL40, it was Oscar Piastri's turn to drive for the constructors' champions on Thursday, but the Australian's afternoon was cut short by a fuel systems issue.

That meant McLaren totalled only 48 laps, more than 100 fewer than Mercedes and Ferrari completed on a day when Aston Martin belatedly made their first appearance at the behind-closed-doors event, which is giving teams a first chance to test their all-new cars for 2026 after the introduction of new power unit and chassis regulations.

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Piastri said: "Unfortunately, a few issues today. We had a fuel systems issue which cut our day a bit short, but I know the team is working really hard to get that fixed and get us back out for as many laps as we can tomorrow."

After delivering highly productive efforts on Monday and Wednesday, Mercedes used the last of the three days they are permitted to run at the five-day event to amass another impressive lap count at the Circuit de Barcelona-Catalunya.

Hotly tipped by many paddock insiders to start the sport's new rules era at the front of the grid, Mercedes continued their extremely smooth start to the pre-season as Kimi Antonelli and then George Russell racked up a total of 167 laps.

Antonelli had set the fastest time of the event in the morning, only for Russell to better it in the afternoon as the Brit recorded a 1:16.445 to sit more than half a second clear of his team-mate, and almost two seconds ahead of any other car.

While it remains too early to read too much into the times, especially given Mercedes are further through their programme than their traditional rivals at the front of the grid, the Silver Arrows' performance has been hugely impressive.

Russell said: "The car so far has been working well but it's not about how well it works, it's about how quick it goes around the track, and we don't really have an indication of that at the moment.

"We're in a reasonably good place but I'm sure things are going to change a lot between now and the next Bahrain test. I'm sure people are going to be bringing upgrades to the car, so still very much early days."

After debuting largely in the wet on Tuesday, Ferrari had a strong day of running with Lewis Hamilton and Charles Leclerc in the afternoon, combining for 174 laps.

Hamilton said after his morning run that Ferrari were doing "better" than in last year's pre-season testing and that the 85 laps he managed on Thursday was an "amazing" feat. Leclerc was third on the timesheet behind the Mercedes duo.

The trio of title hopefuls were joined on track by Cadillac and Racing Bulls, with the latter becoming the only team other than Mercedes to use up their allotted running time ahead of the final day of the event on Friday.

Aston Martin finally make it on track

Having said on Monday that they would miss the first three days and were aiming to make it out on track and Thursday, Aston Martin just about met their target as the AMR26 emerged from the garage with Lance Stroll in the cockpit with an hour of the day remaining.

Stroll stopped out on track in the closing moments to bring out the only red flag of the day, but overcoming some gremlins overnight could be crucial to allowing them a full day of running on Friday, when Fernando Alonso will get his first chance to drive the car.

There is great intrigue around the team's first car designed with the heavy influence of team principal Adrian Newey, whose legendary design skills helped Red Bull dominate the start of the previous rules era.

The car ran in all-black camouflage livery rather than the team's usual green, but onlookers immediately noted a car design that appeared significantly different to most others that have been seen throughout the week.

Stroll said: "Everyone did a good job of getting the car ready today. It was a long day for all the mechanics and everyone in the team, pushing flat out to get the car ready. We got a few laps in at the end of the day, and it was feeling good."

With Williams missing the whole event having been unable to get their car ready, seven teams have completed two days of running and are expected to complete their allocation on Friday, while Aston Martin will hope to get a full day on track.

Max Verstappen is among those expected to drive on Friday, with Red Bull having been unable to feature for the last two days after Isack Hadjar crashed the RB22 in wet conditions on Tuesday.

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