A smoke generating unit for a model vehicle controls and varies the rate at which smoke is generated by controlling power to a heater. The model vehicle is electrically driven, and the smoke-generating unit is configured to emit smoke so as to mimic varying emission from a traditionally-fueled vehicle, such as a steam-driven or diesel-driven vehicle. Smoke is generated in proportion to power supplied to the heater. A controller controls the power as a function of various control inputs, such as vehicle engine load, vehicle speed, or user input. Temperature or power feedback may be used as input for a closed-loop control process. A blower for the fan may be controlled via an analog circuit in response to velocity or load input to simulate a steam or diesel locomotive.