If you're conscious about gas mileage forget the wonderful high revving V8 M3. I don't care about how fast the fuel gauge meter drops and when I need a bit of boost, the Circle M button on the steering wheel raises the energy level fast.
I'm keeping my M3, and few years ago I debated between and Evo X and M3. Had the Evo X for 2 years before the comforts of the M3 finally made me give in and get the car I finally wanted. And I DD my M3 all year round. Never turning back and never letting her go.