Hi Buddy.
Look at the condition of the car first. Interior, scuffing ,scratches in roof linings, doors panels etc.Body panels etc.That alone, if the car is immaculate and clean.Its worth looking at.The engine you should take someone with that knows engines.A mechanic or even better a Motor Engineering person.So that he can pin point any unusual sounds of the motor.Take me for granted a M3 ,people tend to hammer them.They are cars build for speed.