An engine-powered vehicle having an automatic power management feature is provided. It includes an engine, a transmission with multiple gear ratios driven by the engine, a final drive which provides axle torque data to the transmission to establish engine torque, and an electronic controller for controlling both the engine and the transmission. The electronic controller has automatic speed control, and it also has a device to input data, receive data, and to evaluate at least one variable during automatic speed control. When the electronic controller receives data input from the engine, transmission, final drive, and device, the electronic controller determines engine rpm and transmission gear as a result of the data received to maintain a selected speed.