Mercedes kept the tempo high on the fourth and penultimate day of the 2026 Formula 1 shakedown at Circuit de Barcelona-Catalunya, topping the times and racking up mileage as the new era cars continued to show their first hints of form. The headline lap came from George Russell in 1:16.445, with team-mate Kimi Antonelli next best on 1:17.081, underlining a strong and smooth three-day run for the Silver Arrows.

The late show belonged to Aston Martin — and it was brief. The Adrian Newey-penned AMR26 finally broke cover near the end of the session, with Lance Stroll completing five laps before the car stopped on track and triggered a red flag. It was a tantalizing first look at a car with striking sidepods and a bold engine cover, but the team will hope Fernando Alonso gets a full run on Day 5.

Mercedes lay down a marker with pace and mileage

There is no trophy for a shakedown. But there is momentum, and Mercedes built it. Russell’s 1:16.445 led the sheet, backed by Antonelli’s 1:17.081 as the teenager added another 90 laps to his growing logbook. Russell clocked 77 laps as Mercedes finished their three allocated days at 168 laps for Day 4 and a hefty 499–502 across the week, depending on the final tally used.

Antonelli sounded exactly how you would want a rookie to sound after a smooth test: confident but grounded. “We go [to Bahrain testing] with high confidence and high hopes because, definitely, it’s been good,” he said. “We did a lot of laps, so really good mileage for the team. I’m happy because I’m learning quite a lot about the car, and just looking forward to being back in Bahrain.”

That last line matters. New rules often mean new problems. Yet Mercedes, while not issue-free earlier in the week, turned their laps at will here and left Barcelona looking organized and ready.

“Mercedes didn’t just chase times — they banked trust in the car.”

Ferrari’s quiet grind pays off in big mileage

If Mercedes grabbed the headlines, Ferrari won the grind. The Scuderia logged a day-high 170 laps (some counts list 174), splitting the work between Charles Leclerc and Lewis Hamilton. Leclerc’s 1:18.223 came with 89 laps; Hamilton’s 1:18.654 came with 85. That is the kind of shared load a team wants when it’s mapping a new car — in this case the SF-26 — under fresh rules.

Hamilton’s verdict sounded upbeat without the hype: “Last year we had a worse start to testing, so this is actually — considering it’s a completely new band of rules — it’s better than we’ve experienced in the past, so I’m really hopeful that continues… amazing [mileage].” The takeaway is simple: Ferrari spent Day 4 learning, and they learned a lot.

“Ferrari look steady. Not flashy yet, but the laps speak loud.”

Aston Martin finally breaks cover — then hits trouble

The most-anticipated car in the paddock, the Honda-powered AMR26, rolled out late with Stroll at the wheel. The design, shaped by Adrian Newey’s vision, drew eyes with its unique sidepod profile and an aggressive engine cover. But the debut was short. After five laps, the car stopped and brought out a red flag. Stroll’s best was a humble 1:46.404 as the team focused on systems checks more than speed.

The silver lining? The car is on track at last. With Alonso slated to drive on Day 5, Aston Martin still has a window to gather critical data before the Bahrain test. The risk, of course, is that their test plan is now compressed. Day 5 becomes important not for glory laps, but just to rack up clean mileage and understand the car’s behavior across runs.

Midfield watch: Racing Bulls reliable, McLaren hit a snag, Cadillac steady

Racing Bulls put up another reliable day’s work and completed their three-day allocation. Rookie Arvid Lindblad banked 47 laps and a tidy 1:18.451, while Liam Lawson added 64 laps with a 1:18.840. Lawson’s summary captured it: “In terms of mileage, yes – we’ve honestly had a pretty strong test in terms of reliability, so that’s been a box ticked. In terms of expectations, it’s very hard obviously – we don’t know where anybody else is.”

McLaren’s day was shorter than planned. Oscar Piastri managed 48 laps and a 1:18.419 before a fuel systems issue forced the MCL40 to stay in the garage. Piastri was calm about it: “We had a fuel systems issue, which cut our day a bit short… They’re all completely different cars, completely different engines to what we’ve had for the last three or four years.” New rules bring teething problems; the goal now is to fix it and run strong on Day 5.

Cadillac, with Sergio Perez at the wheel, quietly ticked off 66 laps and a 1:21.024. There were no fireworks, but steady laps matter more than glory runs at this stage.

“Early days, but Racing Bulls look bulletproof. That’s half the battle.”

Day 4 scoreboard: fastest times and lap counts

Fastest laps on Day 4 in Barcelona:

• 1) George Russell (Mercedes) – 1:16.445 – 77 laps
• 2) Kimi Antonelli (Mercedes) – 1:17.081 – 90 laps
• 3) Charles Leclerc (Ferrari) – 1:18.223 – 89 laps
• 4) Oscar Piastri (McLaren) – 1:18.419 – 48 laps
• 5) Arvid Lindblad (Racing Bulls) – 1:18.451 – 47 laps
• 6) Lewis Hamilton (Ferrari) – 1:18.654 – 85 laps
• 7) Liam Lawson (Racing Bulls) – 1:18.840 – 64 laps
• 8) Sergio Perez (Cadillac) – 1:21.024 – 66 laps
• 9) Lance Stroll (Aston Martin) – 1:46.404 – 4–5 laps

Team lap counts for Day 4:

• Ferrari – 170 laps (some lists show 174)
• Mercedes – 168 laps (Antonelli 90, Russell 77)
• Racing Bulls – 111 laps (Lindblad 47, Lawson 64)
• Cadillac – 66 laps (Perez)
• McLaren – 48 laps (Piastri)
• Aston Martin – 5 laps (Stroll)

By the end of Day 4, every team except Williams had appeared, with Mercedes and Racing Bulls completing their three-day allocations. Mercedes’ total for the week sits at 499 or 502 laps depending on the tally referenced — either way, a strong number for a brand-new ruleset.

What it means heading to Bahrain

Mercedes leave Barcelona with two things that matter: solid speed and trust in the W17’s systems. That breeds calm before the official Bahrain test. Ferrari’s workload was heavy and useful, and the SF-26 looks like a car the drivers can push for long runs already. Racing Bulls can be happy with reliability — a foundation for performance steps later. Cadillac’s steady day keeps them in the mix.

For McLaren, the to-do list is clear: fix the fuel systems issue and get back to long runs. For Aston Martin, Day 5 now carries extra weight. With Alonso set to drive, the aim is simple: gather mileage, validate those radical bodywork choices, and head to Bahrain with a baseline, not questions.

Remember, this shakedown is behind closed doors and spread over five days, with each team allowed three. It is not about lap-time bragging rights. It is about learning. Still, patterns do emerge. Mercedes are efficient and quick. Ferrari are tireless. Racing Bulls are tidy. McLaren and Aston Martin have puzzles to solve, but time remains before the lights go out for real.

Day 5 will bring final answers from Barcelona — including Alonso’s first go in the AMR26 — before the paddock packs up for Bahrain. The new era is here. Now the details will decide who hits the ground running.