i would say bmw because bmw is racing on in F1 circuit consequently their speed and engine becoming faster via experiment being in f1 era.
Why do you think so? Audi is a smarter VW [dot] BMW win every year the "Engine of the Year" and a lot other prizes.
I would have to go with the BMW! I owned an older M5 a long time ago and loved it. The Ultimate Driving Machine.
I think I saw this car while I was partying down in nashville, and must I say the pictures don't do the beamer justice! Much better in person!