What is it? no markings. no wheels, no room for mechanix.

Tiny metal car has green felt or cloth of some type as the base. There is a hole in the top. I am guessing it belonged to some type of track set. It has no identifiable marks. There is no room for mechanics or wheels. It does not appear to have been altered after it's manufacture. Measures about one inch long by 1/2 inch wide. It seems to have been designed to run on its padding.