Apart from those terrible soft plastic Quick Fits, Frog made the following proper car kits, all in 1/16 scale:
They were multipiece and could be motorised, but with a bit of work could be built into surprisingly nice models.
All of them except the ambulance were reissued in the Soviet Union by a company called Novo, but not in all of the Russian issues the chrome parts were plated.
They are rare to the extent of bordering obscurity, especially the ambulance.