A method and system for improving fuel economy in a vehicle. The vehicle is equipped with an internal combustion engine, and a suspension air-spring automatic pneumatic control system. The internal combustion engine is controlled by an electronic engine control module. A load signal representative of the cargo load is generated and fed to the engine control module to cause the engine control module to enter a reduced horsepower mode of operation when the vehicle is less than fully loaded. Alternatively, the load signal is used as a basis for attenuating a fuel demand signal generated by the accelerator pedal deflection when the driver presses the accelerator pedal. The attenuated fuel demand signal is input to the engine control module, causing the engine control module to reduce the fuel consumed by the engine when the vehicle is less than fully loaded.