Yeah. RS4.
Last year at Crail Raceway, I watched a RS4 race a brand new M3. It was a 57 plate M3, 1 day after release.
Its was pissing with rain all day, and the RS4 won every race.
If it was dry, the M3 would have won (As top gear have showed), but the 4x4 system really showed its stuff that day.