Abstract: A gas-based transmission which has a self-regulating mechanical advantage that is continuously--and, essentially, infinitely variable. A high-pressure reservoir receives either exhaust gas from an engine or air from a compressor that is run by the drive shaft from an engine. A pressure regulator on the output of the high-pressure reservoir controls the engine resistance and decouples the engine from the the drive forces. The pressure can be set at a given level which will approximate the power curve for the engine or can be controlled by a computer so that the engine will produce the power desired by the operator at the lowest engine speed capable of producing such power, i.e., the engine will operate precisely on its power curve. The gas or air passes from the pressure regulator to a variable-pressure reservoir.