almost all cars depreciate but there are certain cars that have very minimal depreciation. Buying 2nd hand will help lessen the depreciation. try to buys cars that are considered in demand and probably will still be in demand in a few years time. Cars like the 92' honda hatchback. a friend of mine bought it before when it was in the people's car program for 180K. he sold it for 170K 2 years ago. The Miata is similar, it was being sold around 500K++ when it was last sold here, those last few models still fetch around 500K+.
Rule of thumb is try to buy cars that have known low depreciation, like Toyota and honda. car manufacturers like Nissan, previous mazda (except miata), some mitsubishi, hyundai, kia, daewoo, all american cars, other car manufacturers.