@richardknott @Klaxun @jensorensen
There isn't a class for microcars or quadracycles in the US and Canada with few exceptions.
If it's got 4 wheels it needs to meet the same crash test standards as any other car. So things like the Microlino or Citroen Ami, Renault Twizy etc can't be licensed here.
The major out is if it's got three wheels. Then it gets classified as a motorcycle and exempt. So things like the Polaris Slingshot and Aptera are legal.
The other exception is cars older than 15 years in Canada, or 25 years in the US don't have to meet the standards. So you do see some Japanese kei class cars/trucks roaming around.