Prices vary and dealers and traders are offering as low as £20K for M3's. I still get calls from dealers asking if my car is for sale.
I spoke to the Sytner Group Buyer when I was trying to sell my one and at the time he said that the max they would offer would be £23K! There is a clear decline in residuals for the car and he said it would only get worse.
It's very difficult to predict what your car will be worth in 4 months time.
If you are looking to buy another BMW then trade in/part ex may be the best deal you can get against a new or nearly new car.
F80 M3 Black Sapphire/Sakhir Orange.