Drag forces on models which have the shapes of existing bus bodies and truck-trailer combinations, have been measured. The study reveals that the drag coefficient of these shapes can be considerably reduced with marginal changes in the shape and by add-on devices. A reduction of about 40% in the drag coefficient can be achieved by mere corner rounding in case of bus bodies and for truck-trailers the drag coefficient can be reduced by 25% using add-on roof fairings.