Anybody who has bought a car will tell you that there are tangible points of difference which affect their decision to make a purchase. For example, there are many different models of car which have various characteristics. They may have manual or automatic transmissions, fuel injection systems, be small and versatile, designed for a family or for a couple, have four-wheel drive and also have vast differences in fuel-economy, safety, security and performance. The prospective purchaser can read reports through the motoring press, visit a showroom, sit in a car and test-drive it in order to make a comparison of these features.