Creation of simple vehicle icons

Our company renst vehicles of all kind: cars, motorbikes, vans, buses, trucks, etc. We have about 10-15 different types of vehicles. We would like to have a (very) simple black and white line art drawing symbolizing each vehicle. The style has to be consistent across the whole vehicle range, but at the same time it also has to be really simple so that future drawings can easily be designed when new vehicle types are added. Examples: Mini Clubman, London Taxi TX2, Metrobus double-decker bus, Daf single decker bus, Neoplan single decker bus, etc. We supply 1 picture of each vehicle. The drawing has to be a simple outline of the picture we have provided. See the attached examples (work done by an illustrator who is no longer available).