Doodlebug.

About Doodlebug

Doodlebug or hoodlebug is a nickname in the United States for a type of self-propelled railcar most commonly configured to carry both passengers and freight, often dedicated baggage, mail or express, as in a combine. The term has been used interchangeably with jitney. The name is said to have derived from the insect-like appearance of the units, as well as the slow speeds at which they would doddle or "doodle" down the tracks. Early models were usually powered by a gasoline engine, with either a mechanical drive train or a generator providing electricity to traction motors ("gas-electrics"). In later years, it was common for doodlebugs to be repowered with a diesel engine.