0-60 and 1/4 mile times, are not reasons why someone should buy one car over another. In the case of M3/M5...it depends on what you want. The M3 is smaller, has less power, less torque, and doesn't have a very accessible back seat, but it has less weight, faster performance, and that raw sports car feel. The M5 isn't as nimble, doesn't sport the high-revving feel of the M3, and weighs almost 600 lbs more, but has enough room to seat 5 comfortably, has gobs of torque, looks better (IMO), exudes class, and will snap your head off in any gear.