On a related note, watch this fool woman flip her car (skip to 2:30) due to hitting a gate at what must be no more than 10mph because she can't operate a clutch pedal. How it had enough energy to roll all the way on to its roof I'll never know. I know such egregious idiocy behind the wheel should earn drivers like her a permanently revoked license though.
I think you underestimate just how much energy a moving car has. If you've ever tried pushing a car, you know that it takes a tremendous amount of force to even get it rolling, let alone accelerate it further. Get all that momentum moving up a ramp (the gate) and that's the result.