The S5 feels slow compared to my RS4, though its interior is much nicer. Sounds pretty mean as well. THe rear seat in the S5 is useless.

The M3 sedan is a great looking car, and will spank the S5 all day long onthe track, and an experienced driver will beat up on the RS4 on a track, though a decent suspension on the RS4 will lose much of the understeer.

If I were buying today, and did not need AWD, I would take the M3. More fun for the money.

If you need AWD, consider the 335xi, and with 5 grand into it with chip,exhaust and suspension, you will have a beast. I'm a big audi fan, had a B5 S4, and an e46 M, but the 335i is a better car for the money than the S5...

I'm on hold waiting to see what happens with the latest RS6, and perhaps the RS5. will proably keep the RS4, and may in the meantime pick up a P car.