Microcars and minicars had their real heyday after WWII, when war-damaged economies had to start small. Gas was expensive, and consumers had little money. The result? Small (sometimes tiny) fuel efficient cars.
Oddly enough, many boasted advanced design features. This is because most evolved from war torn aircraft factories which were prohibited from building airplanes after the war but still employed some of the finest and most experienced aircraft engineers.
Most microcars sported one or two cylinder motorcycle or motorscooter engines (usually two stroke designs), and often evolved in three wheeled configurations to take full advantage of favorable tax treatment under loopholes originally designed for motorcycle/sidecar rigs.
They were considered “Kabinenrollers” or “enclosed scooters” and were intended to bridge the gap between motorcycles and “real’ cars. Now, that’s not the whole story. There’s lots of micros and minis, some of them built today, some from the turn of the century.
– gathered from http://www.bubbledrome.org/mm_link.htm