BMW M cars are fantastic machines, so much so that they have a cult following. Between the M4 and the M5, the M5 is the bigger brother and is endowed with 127 more horsepower than the M4 (552 vs. 425 for the M4). The only problem for the M5 is that more power doesn't always mean the car is a winner. The M5's 4,387 pound weight is obese compared to the M4's 3,530 pounds. This particular M5 owner wanted to show the M4 that the bigger brother still reins supreme, so he raised the stakes by tuning the engine to put out 800 horsepower.

Not wanting to be outdone, the M4 owner modified his ride to whirl out 550 horsepower. Which of the M siblings takes the win: the heavy and powerful or the agile and zippy?