The Italian Job (1969)
Directed by Peter Collinson
Wikipedia: "...despite the huge publicity the film would give to the Mini, the car's maker, BMC, were not completely committed to the project. BMC only provided a token fleet of Minis and the production company had to buy the remaining number needed for filming, albeit at trade price. By contrast, the Italian manufacturer Fiat grasped the commercial potential of the film and offered the production team as many super-charged Fiat cars as they needed, several sports cars for the Mafia confrontation scene, plus a cash lump sum of $50,000, but the producers turned down the offer because it would have meant replacing the Minis with Fiats."