Oscar Piastri’s first run in McLaren’s 2026 car has been cut short by a fuel system problem that left him unable to complete more than 48 laps on the penultimate day of Formula 1’s first pre-season test.

Piastri got behind the wheel for the first time on Thursday, a day after reigning champion Lando Norris gave the MCL40 its first laps, but the Australian didn’t leave his garage after the lunch break as the team stripped down the car in search of the root of the issue.

It left McLaren with just 48 laps on the board for the day, less than a third of the daily totals set by engine supplier Mercedes (168) and 2024 constructors title rival Ferrari (174), the latter of which was also completing its second day on track.

Watch the biggest Aussie sports & the best from overseas LIVE on Kayo Sports | New to Kayo? Join now and get your first month for just $1.

Though Norris set a reasonable 76 laps on Wednesday, McLaren’s daily average lap count is the lowest of the established teams to have turned up in Barcelona bar latecomer Aston Martin. Only newcomers Audi and Cadillac have been less productive.

“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,” McLaren performance technical director Mark Temple said.

“We discovered a fuel system problem, which meant we haven’t been able to do all the running we would like.

“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 ahead of tomorrow’s running.

“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 tomorrow.”

But Temple said there were also “positives to take away” about the preliminary signs of the car’s performance potential. Unofficial timing data suggests Piastri was fourth quickest for the day despite not being on track in the afternoon, when conditions were warmest.

“We’ve got a good understanding of where the car is from a baseline point of view,” he said.

“Overall, we haven’t encountered anything too unexpected. The behaviour and handling of the car is in line with what we thought, so nothing is catching the drivers out.

“It’s just about learning and getting to know it, and then as we get more time, we’ll look to try and tweak or tune the car.”

Piastri stars in hilarious new ad | 01:10

Piastri said he had been eager to get his pre-season underway given the sweeping regulations changes tipped to open the competitive order, and the Australian said he already had ideas to improve the car despite the truncated day.

“There’s a lot of challenges this year up and down the grid, so it was good to get stuck in,” he said. “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.

“We have one more day of running tomorrow. 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.”

McLaren did not complete a private shakedown before arriving in Barcelona, preferring instead to run whole-car dyno testing in the build-up to the first test.

Team boss Andrea Stella said the strategy was to maximise development time to put as mature a car as possible on the track in the opening test, with few upgrades scheduled between now and the opening grand prix in Melbourne.

While Thursday was an early setback for McLaren, there are still six more testing days scheduled in Bahrain, in more representative conditions, before the Australian Grand Prix.

Mercedes has also proved through its relentless three days of testing that its power unit has no obvious major reliability issues, which will stand customer team McLaren in good stead.

McLaren will split its final test day between Norris and Piastri.

Only Mercedes and Racing Bulls have exhausted their three-day testing allocation for the week. All teams bar Williams, which is skipping this test due production delays, will be on track with McLaren on Friday.