Yeah... if you want to make money on cars --and even then this is still a gamble,
Pick something you know is popular (like Viper, high-spec Mercedes, top of foodchain Mustang, exotic, etc.) and watch them like a hawk for sales price for the 3-7 years old mark.
You need to buy the best one you can at the bottom of the depreciation curve. Miss the curve, miss the potential profit. Note that the places with 15 Vipers for sale are your competition.
The principle applies to anything, just the likely profits on a Toyota Camry handled this way aren't much.