The first model cars, for example the Beelt, came in a lot of different coloures, this because they were handpainted. The were moulded with transparant plastic and later they ware painted. Later all models were moulded with coloured plastic and came in the 'normal' LEGO colours red, white, grey, blue and black. 

The baseplate of the model cars are not glued to the model. There are a few exeptions: The Volkswagen Beetle (long model, 260) and the Mecedes Benz 190SL (266/666).

The most cars have transparant plastic headlights. These are mostly missing in the nowadays models.