McLaren's testing day was curtailed by a fuel system problem on the fourth day of Formula 1's 2026 Barcelona shakedown, with Oscar Piastri completing just 48 laps. Mercedes continued its strong form, amassing 168 laps and setting the fastest time, while Aston Martin made its long-awaited debut with Lance Stroll before a stoppage caused a red flag. Ferrari also enjoyed productive dry running after earlier wet conditions.
The fourth day of the behind-closed-doors Barcelona shakedown saw mixed fortunes for the teams preparing for the 2026 Formula 1 season. McLaren, on its second day of running with the MCL40, handed duties to Oscar Piastri after Lando Norris completed 62 laps the previous day. Piastri managed 48 laps in the morning before a fuel system issue sidelined the car for the afternoon. Performance technical director Mark Temple explained, “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. 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.” Piastri added, “We had a fuel system issue, which cut our day short, but the team’s working hard to get that fixed and back out tomorrow. 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.”
Mercedes wrapped up its three-day allocation with impressive reliability, as Andrea Kimi Antonelli and George Russell combined for 168 laps. Antonelli set a 1m17.081s in the morning, while Russell improved to 1m16.445s in the afternoon, topping the unofficial times. Antonelli noted, “We go [to Bahrain testing] with high confidence and high hopes because, definitely, it's been good. Obviously, we had our issues during the shakedown, but we were able to fix them and now we can be sure that in Bahrain we can more or less hit the ground running there as well.”
Aston Martin finally debuted its Adrian Newey-designed AMR26 late in the day, with Lance Stroll completing five laps before stopping on track, triggering a red flag minutes before the 6pm finish. The unpainted car featured a unique sidepod and engine cover design. Stroll said, “Nice to be back in the car after a few weeks off. Everyone did a good job in 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, so we got a few laps in at the end of the day and it was feeling good.”
Ferrari shifted to dry conditions after Tuesday's rain, with Lewis Hamilton running 85 laps despite an early spin on cold tires, and Charles Leclerc adding 85 more for a combined 170. Hamilton described it as “amazing” to complete that mileage. Racing Bulls and Cadillac also ran, with Liam Lawson (64 laps) and Sergio Perez (66 laps) contributing to the session. Alpine, Audi, Haas, and Red Bull sat out Thursday but plan to return Friday. The shakedown emphasizes mileage over pace, with Mercedes leading at 499 laps total.
