They should have swapped the cars round each time, just to normalise any difference in the track surface. Or run two of the same model against each other a few times to see if the track surface made a difference. It looks like it's an airfield track, and if so, then the surface could be pretty patchy with different repairs of different quality at different places.
Even so, it's a very interesting comparison - given the much lower cost of the BMW I would have expected it to lose by a substantial margin. My brother-in-law has the RS4 Avant and even 'though I've owned a number of 3 Series Tourings, I'd have to say that the Audi interior is better, and is probably the only black interior that works for me - I'm not usually a fan of black. AS you can see, I preferred my Tourings in less funereal clothing:
And no, that beige interior didn't show the dirt like you might expect, even when I put my MTB in there:
And interestingly, my previous Jeep Grand Cherokee couldn't fit the MTB inside without taking the front wheel off (the bike, not the car). Which on a bike with hydraulic disc brakes is a pain. Give me a Touring/Avant over an SUV any day...
And finally, no - I'm never going to buy a BMW with the chipmunk grill, so that's the M3 Touring off my list, sadly.