The Isetta. Believe it or not you used to see the odd one on the road during the sixties.
My dad had one of these for a while when I was a kid. Don't know where he found it and I've never seen another. He sold it to a young guy who said he was taking it to Quebec. Not driving it I hope but back then you never knew. It differed from the Isetta in that it was a tricycle with only one rear wheel.
https://www.youtube.com/watch?v=Ke_sPTaaZkcThe Germans built a few bubble cars after the war when they were trying to get their industry back up and running. Heinkel of course was an aircraft manufacturer and Messerschmitt was another which built a tricycle but with tandem seating like an aircraft.
https://www.youtube.com/watch?v=llB25Vn92uM