Diesel engines are widely used in heavy-duty vehicles. Such vehicles are frequently operated in fleets and are re-fuelled centrally with fuel delivered direct from the supplier. In the light-duty vehicle sector, recent advances in engine design now also allow light-duty diesel engines to compete with gasoline engines on performance grounds.

Lightduty vehicles are generally re-fuelled through retailoutlets. Although the emphasis differs, in both sectors the customers will be generally looking for fuel that provides economy, power, reliability and environmental acceptability.