Carlos Sainz has revealed that adapting to the Mercedes power unit at Williams has been the “biggest change” following his switch from Italian Formula 1 giants Ferrari.
Sainz got his first taste of a Williams F1 machine during a filming day and subsequent post-season test at the Yas Marina Circuit in December.
Since then, the Spaniard has driven the FW45 during a two-day TPC programme in Barcelona and completed a shakedown of 2025’s FW47 at Silverstone.
Williams will be Sainz’s sixth F1 team in 11 seasons, but the first time racing with a Mercedes power unit and he described how that change has been his “biggest” since joining the Grove-based outfit.
“I can talk a bit about Abu Dhabi and how that first laps went,” Sainz began, speaking to select media including Motorsport Week.
“Definitely the thing you feel the most when you change teams, the moment there’s a power unit involved, it’s the power unit.
“The noises, the vibrations, the sound, everything just changes completely, so even if I went out on the pitch trying to understand the aerodynamics and the tyres and the feeling of the mechanical sides of the car, the only thing I could have to adapt for the first few laps was just how different a power unit can be.
“So yeah, that’s probably the biggest change, also the way the power unit operates in terms of switches, especially nowadays in Formula 1 with so much going on on our steering wheels, with the deployment, the battery, things like this, procedures, safety procedures of the engine and the power unit, it’s all definitely the biggest change that I’m having to adapt so far in Williams.”
Williams FW46 ‘better than expected’ – Sainz
Sainz will have different expectations ahead of the 2025 season compared to last year, having left a race-winning outfit in Ferrari to compete for the squad that finished ninth in 2024’s Constructors’ standings.
Despite the differences between Ferrari and Williams, Sainz was pleasantly surprised after driving the FW46 in December, just a day after finishing second in the Abu Dhabi Grand Prix.
“Honestly speaking, I think first impressions are very important, because you only have one chance to make a first impression, and that was very positive,” he said following the FW47 launch at Silverstone.
“Because at Williams, in Abu Dhabi, I found a car that was honestly a bit better than I thought, or better than I expected, obviously with some deficiencies compared to the cars that I’ve been driving, but not massively far off.”
Sainz’s assessment of the FW46 was great news to Team Principal James Vowles, who confirmed the Spaniard told Williams it was heading in the right direction.
“It was incredibly useful and powerful having him testing with us in Abu Dhabi because we were able to understand where our weaknesses lie relative to a car he’d driven just a few days before but had winning potential, and more importantly, make sure that the direction of travel that we’re in, which I’m pleased to say is correct, was on the right pathway,” Vowles explained.
