A lot of us of a certain age have a nostalgic interest in a particular age of micro cars, from about 1948 to about 1970 when there was a boom, and we tend to remember these as proper micros and bubbles. However small cars were made from the earliest days of motoring. Some of these were popular like the Peugeot Bebe and Austin 7, and these just about fit into the broad range of "Micro". Less well known ones were even smaller, like many small volume cars, prototypes and home-made ones, often single seaters like the Busy Bee.
Since the 1948-1970 boom there have been few micros marketed by manufacturers of any size, but lots of small volume micros, sans permit vehicles, "Kei" cars in Japan and endless 'schmitt and Isetta derived micro concept cars, and of course the Pod. The Smart car has been by far the most successful of the modern 'micros', with G Whiz and Aixam being seen occasionally.