http://www.m5board.com/vbulletin/showthread.php?t=69799A blue RS4 sedan vs a Titanium Silver M5, both with wintertyres.
Some key points below:
"Driving the M5 in the snow is effortless and a childs playthanks to it's electronics sensors"
"The engine of the M5 cannot be compared, there is nothing you can compare it with. So much of Jekyll and Hyde -at the same time!"
Weight of the M5 as tested: 1970 kg. 0-100 km/h in impressive 4,73 s
Weight of the RS4 as tested: 1870 kg (!). 4,67 s.
At 130 km/h the M5 will pass the RS4:
M5 0-200 km/h: 13,7 s
RS4 0-200 km/h: 15,65 s
0-402 m M5: 12,68 s and 192,4 km/h
0-402 m RS4: 12,86 s and 180,6 km/h
The BMW M5 and RS4 was dynoed on a Rototest notice that the RS4 lacks approx. 17 HP, clocking in at 403 HP. The BMW M5 gave 3 additional HP (510 HP) when measured.
RS4 averaged 1,5 liters / 10 km and M5 1,7 liters / 10 km
Bottom line: "We cannot say which is best since they are so different, but the Audi takes a lot of points on the winterroads."
"You can wait a few years to let them depreciate to half. And buy both" (not a bad idea )
Summary for the RS4 "Class bully":
In many years Audi have tried to build a car that matches the best in power and not at least driving dynamics. With the new RS4 they have built that car -on all surfaces. Best in class.
Summary for the M5 "Megalomaniac":
Big, heavy and reasonably comfortable, and along with a competent driver can drive the xxx of most car there is. M5 might be the most impressive car in it's kind. Hightec in a way that no other has.
Both cars scored 61 points /100.