The RS6 vs. M5 by Sport Auto. Please note that the M5 figures
are from the test 3/1999 and there has been a new test since where the M5 performs better, 41 points. (there have been upgrades over the years.)
But frankly speaking I find it hard to see how a car can go from 35 points to 41 in just a facelift.

Very nice website: Track Challange RS6 vs. M5

Compare the above website with this:
Sport Auto Scan