This study describes a novel approach utilizing waste heat from the exhaust gas for comfort heating of the passenger compartment of a vehicle with an air-cooled engine. In the devised system, a water stream heated by the hot exhaust gas was sent to the passenger compartment of a commercial minibus with an air-cooled engine, and the system was tested under various operating conditions. Variations of the temperatures at several locations inside the vehicle were monitored while ambient temperatures were -3, 0, 5 and 10 degrees C and there were various numbers of passengers on board, It is found that the system shows a reasonable heating performance while consuming no extra fuel for this purpose, and experimental data is in good agreement with numerical results based on heat loss calculations, Results show that when the ambient temperature is above 10 degrees C and the engine speed is above 2500 rpm, the system yielded comfortable compartment temperatures. Compared with alternative methods using extra fuel for comfort heating, the proposed system decreases vehicle operating costs and environmental pollution caused by the heating system as well as causing a lower global warming. (c) 2005 Elsevier Ltd. All rights reserved.