Sérieux comme le plaisir (1975)
"In Serieux comme le plaisir, two men and a woman live quite happily together in a romantic liaison. The woman is probably wealthy anyway, so the trio doesn't worry much about money. One day they decide to take a trip in their beat-up car, managing the whole affair in their own special, insouciant manner. They are followed by a suspicious policeman who thinks there's something fishy about this group..."
Directed by: Robert Benayoun
Starring: Jane Birkin, Richard Leduc, Raymond Bussières, Georges Mansart, Paul Demange, Hubert Deschamps
Links: IMDb, Movie posters, Movie stills