Yep...its a real car. BMW built this car, an Italian design, under license as the BMW Isetta. The originals were two seaters. This is an enlarged four passenger Isetta 600.
Some might remember the Isetta as Erkle's car on 'Family Matters'.
Cars of this ilk were very popular in Europe after WWII until the early sixties: http://en.wikipedia.org/wiki/Isetta