I'm trying not to drag this on, but the source with incredibly accomplished drivers who spend their lives racing the Nurburgring says 8:13 for the M5. I really don't believe 7:52...a Murcielago with the same weight (OK, 100lbs lighter) lapped in 7:50 with 70 more horsepower and I-don't-know how much more torque, but the M5 only has 384. It's hard to imagine a 4000+ pound, 192-inch sedan lapping the Ring in 7:52 with only 384 lb-ft. of torque...Maybe 8:08, but seeing how that source said the 997 Carrera laps in 8:16, I don't exactly trust them. The old Carrera lapped in 8:17, and I've seen times of 8:11, 8:12, and another 8:12 for the 997. You can't trust anyone without a proof of their time anymore - one of the 4 U.S. magazines just said that the STS-V - ha! - lapped the Nurburgring in under 8:00, and that is clearly BS. They're a lotta claims out there, but you have to have a trusty source like track-challenge.com or Sport Auto. But I'd be glad to see some proof...no arguing with that.
I have a lotta trouble thinking the RS4 will lap in under 8:00, but tailpipe, you seem pretty confident about your claims, like you have a brother or a best friend who lapped the Ring in an RS4 himself. Well, I hope...