Oscar Piastri's first taste of new McLaren cut short by technical gremlin

Oscar Piastri's first proper hit-out in McLaren's new car came to an early end, hampered by a mechanical gremlin.

On the fourth morning of F1's pre-season shakedown in Barcelona on Thursday night (AEDT), Piastri completed 48 laps in the MCL40 before the team identified a "fuel system issue" in the lunch break.

It required an "extensive investigation", which took him out of running for the rest of the afternoon.

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In a statement, Piastri said it was still a productive first day on track, despite the hiccup.

"It was nice to be back out today, especially in the new car. There's a lot of challenges this year up and down the grid, so it was good to get stuck in," he said.

"We had a fuel system issue, which cut our day short, but the team's working hard to get that fixed and back out (Friday).

"These cars are completely different to what we've had the last few years. That's part of what this test is about.

"We've already identified a few things that we can try to improve on the car to make it feel a bit nicer."

The five day pre-season 'shakedown' is taking place behind closed doors - no external media or even photographers are permitted - at the Barcelona track that hosts the Spanish Grand Prix. Each team is permitted to run on three of the five days.

After McLaren opted to sit out of the first two days, Piastri watched from the sidelines on Wednesday night as his world champion teammate Lando Norris got the first taste of the car. The pair will share driving duties on the final day of the test on Friday night (AEDT).

"We'll continue to get used to the car and get a good read on how different things feel. Then we'll find a good direction to make the car quicker and feel nicer," Piastri added.

McLaren technical director Mark Temple said the issue only highlighted the importance of pre-season tests, particularly as F1 enters a new regulation era.

"It's just about learning and getting to know (the car), and then as we get more time, we'll look to try and tweak or tune the car," he said.

"This is a shakedown and is meant to help us identify any issues so we can understand and solve them going into Bahrain, so that's our big focus as we go into the final day.

"Of course, it's a shame we could not run in the afternoon as every minute of track time is precious at such an early stage of the season ... the car is very complex, so we decided to bring the car back into the garage and strip it down to fully understand where the problem is coming from."

Elsewhere, Lewis Hamilton also got his first taste of Ferrari's new challenger.

The seven-time world champion suffered through his first season without so much as stepping onto the podium in a grand prix in 2025.

"When you come to the test you always want to get a lot of mileage (and) today I did 85 laps in the morning which is amazing," Hamilton told Formula One television.

"Last year we had a worse start to testing. So this, considering it's a completely new band of rules, it's better than we've experienced in the past.

"I'm really hopeful that continues."

Hamilton's old team Mercedes has shown incredible reliability in the opening test. George Russell has set the fastest time of the test, with a 1:16.3.

After Barcelona, the F1 circus has two official tests, which will be fully broadcast and open to media, in Bahrain.

The season-opener in Melbourne is on March 8.