What about dressing up as different nationality fighter plane pilots?
You could then do the two BMW's in German fighter plane style, Lambo in Italian fighter plane style, Subaru obviously as the Japanese and then the Lotus as the good ol' British example.
Could decal up the cars in a similar fashion to the below example then (bar all the rivets as that might be a bit OTT).
Edit: Can't really see that as being offensive to the French, ...I mean they do have a sense of humour at least, unlike the Germans. (Joke)