If you look at prices from Sytner of Sunningdale you'd be forgiven if you came to the conclusion that a second hand beemer is more valuable than a brand new one
BMW AUC prices vary wildly. They seem set their initial price super high then after a few months they may cave and knock 3 grand off in a blink. Dealers in the proximity of higher population and towards the south tend to have higher prices too. Even then though, if they don't shift the car, they'll knock big bucks off it, and probably still making a tidy profit.