Auf eine ganz krumme Tour (1964)

Don Giuliano Niccolini Borges, Roman prince and member of the Pontifical Noble Guard, is very much attracted to Jane, an English girl accompanying him on a pleasure trip to Switzerland. He has plans for hanky-panky along the way, but Jane has her own motives as she's only with him because his car has a special-identification license plate and can go through customs without inspection.