You actually are much less likely to die if a small car hits you. If a big car hits you, you're kind of screwed.
The bigger vehicles slam you down and then drive over you, for a much less pleasant experience.
You'll be sent into the air. Not 400feet or anything, but you will not simply be rolling gently over the vehicle, then hop off and continue your day.
How high do you think someone can fly without cracking your skull when you land on pavement?
Where did I say I'd be rolling gently over the vehicle?
I'd much rather have the chance of rolling, flying, or at least something that will allow my body the chance to lose momentum. Rather than within 1 second find my skull under the wheel of a 9,000 lb vehicle.