Abstract: A multi-cylinder Otto cycle internal combustion direct compound engine for motor vehicles with an exhaust-gas turbocharger providing direct turbo compounding upon the engine control module receiving a speed signal indicating that the vehicle is traveling in a predetermined cruise-speed mode. Upon receipt of the signal the module turns-off each fuel injector feeding a second group of the cylinders, while maintaining fuel injection to a first group of cylinders and fully opening the electronic intake-air induction throttle. As a result the unfired second group of cylinder pistons are driven solely by compressed inlet-air pressure during the time the vehicle travels at or above a predetermined light-load cruising-speed, while positive pumping work occurs in all the cylinders. The engine thus conserves fuel during light load cruising speed while maintaining low pollutant emissions.