Now, yes, one car features stock turbochargers and the other has upgraded turbochargers so that is obviously a huge variable. It is not a perfect or fair comparison but things rarely are perfect or fair in a race.
Still a very interesting race to see however especially considering the result. The camera car gets maybe a slight jump opening up a lead on the 4Matic E63. This lead is held through a gear and then the 4Matic E63 starts to pull. The race ends as the turbo upgraded E63 starts to stretch its legs and pull past.
What this shows is clearly the 4Matic car is making more power. However, it also shows that the weight penalty of the 4Matic system and its increased drivetrain losses are a large factor. If both cars had upgraded turbos the rear wheel drive vehicle would likely win this race. The 4Matic adds around 200 pounds for those wondering.
Hopefully we see more runs like this to put the two E63 drivetrains in context. As of right now, it seems roll on races will favor rear wheel drive and going from a stop will favor all wheel drive. Nothing earth shattering that we did not already know.