I don't know why I didn't think of it before, but a C5 Corvette Z06 (2002 and newer make 405hp, 2001 makes 385) will blow the doors off anything under $40k in a straight line and in turns, and they can get over 20mpg on the highway. The interior won't be quite as nice as in the M3, but it's more than nice enough for daily driving, and if you were going to buy an S2, the suspension won't be too stiff to you. Also, aftermarket parts are readily available and the LS6 is more than durable enough to be daily driven at ~450 whp.