With the launch of the new Mercedes AMG GT 63s 4 Door, they have created the most powerful and quickest factory car in their current fleet due to it's all wheel drive. The car has 639HP and accelerates 0-100km/h in 3.2 seconds - on top of that it's a 4 door sedan!
Once the Project One hits the market, then this will be the most powerful.
The car that I tested costs an incredible US$241,000
Vivaldi's Winter by Mike Block
Cat Dance by Man DeLorean