All details seem to match indeed:
https://commons.wikimedia.org/wiki/File:1965_Fiat_1500_Convertible_(9066956354).jpg

Actually, according to this forum post, the P2 was officially sold. Same with the Opel, MikeH mentions selling a '53 for 25$.

The cabriolet looks like a Fiat 1500 Cabriolet, I'd say.

Is the location nearby an European embassy?
AFAIK the Ford P2, maybe the Opel either, was never officially exported to the US, so they may have been cars, owned by employees of an embassy.

This picture dated 1965 accompanied a column in the Washington Post today:


The column was about the building (Halcyon House) but I think we can all agree the foreground is more interesting.

Left to right, I see a 1958 Ford station wagon, a Volkswagen convertible, a British roadster (Triumph TR3?), a circa-1954 Opel Olympia Rekord convertible sedan, a circa-1959 Ford Taunus station wagon, a sleek little roadster I don't recognize (French? Italian?), a Peugeot 403, and a 1964 Ford Galaxie 500

It's an incredible assortment. If this appeared in a movie we would be hard pressed to choose just one to list.