When will teams know if they got it right?

Formula 1 is in a moment of pause. The 2025 racing cars have been wheeled into storage, and the racetracks have fallen silent. But inside the top-secret F1 factories, each team is facing a winter like never before. Revised rules for 2026 are reshaping the cars and redefining what powers them, and that means the pressure is on for the hundreds working back at base.

Before diving into the future, the team at Brixworth, the home of Mercedes High Performance Powertrains, are marking the end of an era. It’s here that the engine - which drove Mercedes to eight straight Constructors’ Championships between 2014 and 2021 - first came to life. Brixworth boss Hywel Thomas has planned a very special celebration to mark the end of this engine cycle and our expert guides Sarah Holt and Holly Samos were there to join in the festivities. This is an important time of transition for Formula 1’s engine suppliers. Thomas and his Brixworth team have been developing the new engine that will power Mercedes and three other teams, on the grid in 2026.

There is parallel work going on at Brackley, where Mercedes Technical Director James Allison is overseeing all other aspects of the new season’s car design. The British engineer has more than three decades’ experience in F1 but even he is a little daunted by what he calls the “biggest ever” rule change in the sport’s history.

While the work intensifies inside the F1 factories, it is, in contrast, time for the drivers to unwind. Italian Mercedes star Kimi Antonelli is heading home to spend some time with his family and friends, while Haas driver Ollie Bearman is holidaying in the Maldives before spending Christmas with his family in Monaco. Back at base, the Haas team are hard at work preparing for F1’s new era in 2026 and that means both sides of the garage are collaborating too. Laura Muller - who works alongside Esteban Ocon and is an F1 trailblazer as the sport’s first female race engineer - has just wrapped up her first season on the pitwall. Like Bearman, she knows the experiences of 2025 will help her navigate what lies ahead.

F1 race-winner Valtteri Bottas is preparing for his return to the grid with the Cadillac Formula 1 team in South Australia. But even in an idyllic spot for winter training, the Finnish favourite is already counting down to pre-season testing and getting to the first race in Melbourne, Australia as he starts the next chapter of his F1 career.

F1: Back at Base is an IMG Production for the BBC, hosted by Rosamund Pike.

Co-hosts & Executive Producers are Sarah Holt and Holly Samos.