The tiny Trabant
in its various versions was the most common product of the East German automobile industry. This is a model of the military version Trabant P601A KübelWikipedia
has more information about the military and civilian versions of the Trabant.
This item consists of 5 models on a sprue, 3 with roof and 2 open-topped.
Another Wargames Blog
has a picture of a conversion.