Here’s Ttyymmmm’s picture of the Champs Élysées (edit: not there because the orientation of the Arc de Triomphe is wrong. Might be Avenue Foch) in the 1960s from earlier.

I’ve identified most of the cars that are near enough to be seen clearly.

But there’s a problem. What’s the little red one in the middle that looks like a Fiat 500 or a Goggomobil but isn’t?

Update: it’s probably a Vespa 400 unless anybody has any better ideas.