Mercedes piles on mileage while Aston Martin finally runs, and McLaren’s test stalls late

The fourth and penultimate day of Formula 1’s 2026 Barcelona shakedown underlined a growing divide between teams who are already in rhythm and those still scrambling to get on track. While Mercedes continued its methodical accumulation of mileage, Aston Martin finally appeared after days of delay, and McLaren endured a frustrating interruption to its programme.

Mercedes once again split duties between Andrea Kimi Antonelli and George Russell, both drivers returning to the cockpit after completing more than 90 laps each on the previous day. Thursday’s running mixed long stints with shorter bursts as the team worked through power unit modes and baseline understanding of the W17. Russell set the unofficial fastest lap of the day, but lap times were secondary to the real priority in Barcelona: reliability and data.

By the end of the session, Mercedes had exhausted its three permitted shakedown days and emerged as the clear mileage leader among the grid. The W17 ran consistently throughout the week, and feedback from both drivers suggested a strong foundation heading into pre-season testing.

Antonelli said the team leaves Barcelona with confidence, acknowledging earlier issues but emphasising that solutions had been found. He added that the car now feels ready to hit the ground running when testing resumes in Bahrain.

At the opposite end of the spectrum, Aston Martin finally rolled its 2026 challenger onto the circuit late on day four. After transporting the car to Barcelona on Wednesday and delaying its debut to complete final preparations, the team sent Lance Stroll out in the unpainted AMR26 during the final hour of running.

The Adrian Newey-designed car completed just five laps, offering a first glimpse of its distinctive sidepod and engine cover design. The brief outing ended prematurely when Stroll came to a halt near the end of the session, triggering a late red flag moments before the scheduled finish. Fernando Alonso is expected to take over driving duties on the final day.

McLaren’s day proved mixed before turning frustrating. Oscar Piastri took over from Lando Norris and completed 48 laps in the MCL40 before the team encountered a fuel system issue. The problem forced McLaren to halt its running early while engineers began investigating the fault.

Piastri said it was encouraging to spend time in the new car but admitted the interruption cut short valuable track time. McLaren’s performance director confirmed the decision was taken to strip the car down fully to identify the cause before resuming running.

Ferrari enjoyed a more productive return to dry conditions, with Lewis Hamilton completing 85 laps in the SF-26. Despite an early spin at Turn 11 on cold tyres during his out-lap, Hamilton described the day as positive and welcomed the opportunity to finally assess the car properly after limited wet running earlier in the week.

Elsewhere, Liam Lawson returned to the track for Racing Bulls, completing what would be the team’s final day under the three-day limit. Cadillac also reappeared quietly, with Sergio Perez logging laps as the American outfit continued its gradual integration into the field.

Several teams elected not to run on Thursday. Alpine, Audi, Haas and Red Bull all sat out the day, with Red Bull focusing on repairs after Isack Hadjar’s crash earlier in the week. Spare parts were flown in from Milton Keynes as the team works to ensure it can return for the final day.

As the shakedown moves toward its conclusion, Mercedes leaves Barcelona with momentum, Aston Martin finally has its first data in hand, and others face a final opportunity to extract answers before the long journey to Bahrain begins.