Are you sure it was the new M5? You said late model. Up to the '03 model, it was a V8 @ 400hp. '05 on has the V10. Actually, the V8 is quicker to 60mph. After that, the V10 kicks in. I routinely race my buddies '03 M5 with my SRT-8. I usually win. Haven't done it yet with the Crossfire.