Mercedes once again topped F1 Barcelona testing Day 4 with George Russell posting the fastest unofficial lap time of the week so far, while Aston Martin AMR26’s track debut was marred by a late red flag.
The Silver Arrows wrapped up their allocated three-day run in the Spanish shakedown, having accumulated a staggering total of laps that far outpaced rivals, building invaluable data ahead of the official Bahrain test.
Morning activities kicked off with a limited field of five cars on track as Mercedes, Ferrari, McLaren, Racing Bulls, and Cadillac took center stage, while absences from powerhouses like Red Bull, Alpine, Audi, Haas, and Williams highlighted the staggered shakedown format designed to manage testing limits.
Kimi Antonelli in the Mercedes W17 seized control early, clocking an impressive 90 laps and setting a morning benchmark of 1:17.081, refining power unit modes through a blend of long runs and qualifying simulations that showcased the W17’s unflinching durability.
Antonelli’s session built directly on Wednesday’s efforts where he and George Russell had already amassed over 180 laps combined, allowing engineers to dissect tire degradation patterns and aerodynamic efficiencies critical for the 2026 grid’s parity push.
Russell took the reins of the Mercedes W17 in the afternoon and proceeded to set the day’s—and week’s—benchmark with his blistering 1:16.445 after 78 laps, eclipsing Antonelli’s morning flyer by six-tenths.
This effort propelled Mercedes to another 1-2 on the timesheets, their combined 168 laps on Thursday equating to over two-and-a-half Grand Prix distances.
However, the highlight of the day was the arrival of the new Aston Martin AMR26 which rolled out for its maiden laps under Lance Stroll’s command, just one hour to the conclusion F1 Barcelona testing Day 4.
Clad in a stealthy all-black testing livery, the Honda-powered beast masterminded by Adrian Newey in his first Silverstone project featured eye-catching sidepod and engine cover innovations that diverged sharply from the pack, hinting an aggressive downforce concept.
Stroll managed just five installation laps at a leisurely 1:46.404—over 29 seconds off Russell’s benchmark—before halting on track, triggering a red flag that prematurely curtailed proceedings minutes before the 6pm close.
The overdue debut, after skipping Days 1-3 due to production delays, squeezed Aston’s shakedown into a single afternoon, but mechanics’ round-the-clock efforts ensured at least baseline systems checks, with Fernando Alonso slated for Day 5 to maximize their quota.
Unofficial 2026 F1 Barcelona pre-season testing Day 4 Results
Mercedes tops F1 Barcelona testing Day 3, McLaren MCL40 makes track debut
Meanwhile, Ferrari’s Lewis Hamilton and Charles Leclerc validated their new Ferrari SF-26 with a total of 170 laps with Leclerc posting the third-quickest time of 1:18.450, roughly 1.778s adrift of Russell.
Hamilton delivered a solid 87 laps, his best efforts landing him sixth overall despite an early spin at Turn 11 on cold tires—a minor hiccup in otherwise productive dry running after the team opted to skip Day 2 and 3.
Oscar Piastri’s debut in the McLaren MCL40 promised much but was curtailed by a frustrating fuel system glitch that sidelined the Australian after 48 laps, his best a 1:18.419 placing him fourth, underscoring the complexities of the Mercedes-powered machine under new regs.
Piastri remained upbeat, highlighting the car’s potential despite the setback, as McLaren’s technicians opted for a full teardown to diagnose the issue overnight, aiming for resolution on Day 5.
Racing Bulls having exhausted their three-day quota split duties between Liam Lawson and rookie Arvid Lindblad, with Lindblad clocking the fifth fastest lap after logging 47 laps, while Lawson placed seventh after completing 64 laps in the VCARB 03.
Cadillac returned for for its second day focusing on baseline setups, with Sergio Perez’s best effort placing eighth after logging 66 laps.
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