Scootacars

Scootacars were originally used in fair ground rides, these were then taken to the roads for use there on a daily basis. They had engines up to 250cc and no suspension.



Scootacars were made with streamlined bodies like the photo below.

The wheels were usually smaller, There is a marque with the name scootacar as well.  The Peel 50 is a scootacar.
Photo below


Then smaller again is the monkey car which was a slot car that carried a live monkey

I am no expert on the subject but I hope this helps
Other small cars can be found under Shell Mileage Marathon.