Sauber has revealed its 2025 Formula 1 livery and car - the final F1 car it will produce before it becomes the works Audi team in 2026.
Like its predecessor, the 2025 C45 - unveiled at the F1 75 launch at the O2 Arena in London - features a striking green for the team's second year being entered as the 'Stake F1 Team'.
That Stake title sponsorship deal covers the two-year period bridging the gap between Sauber's Alfa Romeo deal and Audi's entry into F1 from next year.
Sauber is heading into 2025 with a refreshed driver line-up of Nico Hulkenberg and rookie and Formula 2 champion Gabriel Bortoleto.
While its focus is likely to be biased towards 2026, the point at which Audi enters in addition to the start of a new chassis and engine rules era in F1, Sauber also needs to show it has made progress this year following a disappointing 2024.
Chief operating officer and chief technical officer Mattia Binotto said: "We have made significant advancements in aerodynamics, efficiency, and overall balance, all of which will be key in making us more competitive throughout the season."
Technical director James Key added that the C45 incorporates a "full revision of our aerodynamics, new front and rear suspension, updated cooling systems, weight reduction and improved & refined mechanical set-up options.
"Of course, the development race never stops and performance is all relative, particularly with such an incredibly tight field, so we already have a plan in place to bring further upgrades early in the season which the team has been working on for some time."
It faced a number of operational and trackside issues last year and finished last in the F1 constructors' championship, managing only a solitary points finish: an eighth place from Zhou Guanyu at the penultimate race of the season, the Qatar Grand Prix.
Both Zhou and team-mate Valtteri Bottas were dropped in favour of Hulkenberg, returning to the team he previously drove for in 2013, and Bortoleto, who got the nod in a youth-vs-experience decision from Sauber senior management at the expense of Bottas - who had agreed on the terms of a deal with Sauber but was still waiting to sign it.
Neither of its 2025 drivers were Audi's original target, but the fact that long-time target Carlos Sainz ultimately snubbed it to instead join Williams underlined the extent of Sauber's 2024 plight and a feeling that the project's potential was being squandered.
Check out every 2025 F1 car and livery revealed so far here.
Hulkenberg and Bortoleto both drove Sauber's 2024 car during the post-season Abu Dhabi tyre test, while Bortoleto also said two days of running under the testing of previous cars rules had been completed at Barcelona.
