Mechanical systems de-mystified. Which is better, Quattro or xDrive?

I’m definitely not an automotive engineer, but I do know that a car’s back tires can only take so much horsepower. The BMW M5’s rear rubber is no exception.

BMW chooses to call its SUV-like X5 a “Sports Activity Vehicle,” so it should come as no surprise that it’s named the car you see here something other than “a tall wagon” or “a model wearing our badge that spins its front wheels.” The German automaker has dubbed it the “2 Series Active Tourer.”