Ferrari's Charles Leclerc was top of the timesheets as Formula One wrapped up the season with a final test in Abu Dhabi on Tuesday.
His departed teammate Carlos Sainz had a first full day with new employers Williams, and was second fastest, while a cast of young hopefuls replaced race regulars to get valuable track time in the latest machinery.
Sainz did the second most laps, a total of 146 equivalent to more than two and a half races at the Yas Marina circuit, after RB's Liam Lawson (159).
Leclerc tested Pirelli's 2025 tyre compounds, doing 134 laps and setting a best time of one minute 23.510 seconds while his younger brother Arthur and Italian Antonio Fuoco took turns driving the Ferrari vacated by Sainz.
RB driver Yuki Tsunoda enjoyed a career first test with senior team Red Bull, who had France's Isack Hadjar in the other car, at the circuit that hosted Sunday's final race of the season.
"It’s the first time in the past four years that I have driven a different car. You can physically feel why the RB20 has been fighting for a championship this year, it feels like a very different car to drive," said the Japanese.
"It’s been such an enjoyable atmosphere in the garage. I feel like the car suits my driving style and I haven’t struggled much at all to adapt."
McLaren's race winner Lando Norris was also back in action with Oscar Piastri and Mexican IndyCar driver Pato O'Ward after celebrating their first constructors' championship since 1998.
"I enjoyed being back on track for the morning supporting Pirelli with the development of next year’s tyres," said Norris.
"It’s now time to relax after such an incredible end to the season, the team deserve some well-earned time off before we go again next year."
Mercedes had George Russell and Kimi Antonelli, the 18-year-old Italian who is replacing seven times world champion Lewis Hamilton next season, on track.
Hamilton, who is moving to Ferrari, was in Malaysia for an event with team sponsor Petronas.
Aston Martin had Brazilian reserve Felipe Drugovich and American F2 driver Jak Crawford in action and Renault-owned Alpine tested Estonian reserve Paul Aron and Australian Jack Doohan.
Esteban Ocon had his first taste of the Haas car after leaving Alpine before Sunday's race while Sauber tested with their 2025 line-up of Nico Hulkenberg and Brazilian F2 champion Gabriel Bortoleto.
"Today marked my first day as a Formula One driver. It's an amazing feeling," said Bortoleto.
The 2025 season starts in Melbourne on 16 March.