Technic scale model railroading! After building my static mini-fig scale Fairmont I just had to build a powered version! While the large scale dosen't fit with most LEGO train creations it is quite well scaled to itself. The original had 16 inch diameter wheels. Given the size of the LEGO train motor the scale workes perfectly.
Motor cars came in all shapes and sizes, from 2 man cars to 8 man gang cars. Some had tops and windshields others did not. Some were hand-cranked others had built in starters. Some were belt driven others had transmissions. Seats varied from tractor style to none at all. Being work vehicles the railcar was often hitched to a "pushcart" or small trailer.
The M-19 was a simple car powered by a hand-cranked two stroke engine. The car was belt driven and if you wanted to go in reverse you just started the engine in reverse! The car was light enough that one man could lift the car on and off the rails by himself.