Originally posted by coasterpimp
You would die instantly, or every bone in your body would be broken, have bruised organs, and internal bleeding, followed by death.
If it was genuinely "instantly", like you were at 0mph and then the next moment in plausible time you were travelling at 300mph, then yes, death would be on the cards. But you'd be surprised.
I forget the details entirely, I may, if I can be arsed tomorrow look for the information and videos but; a fair while ago, a man strapped himself to a rocket sled for the purposes of science. Said rocket sled accelerated from a standstill to well over 500mph in an extremely small amount of time and then hit a massive tank of water, decelerating back to 0mph in a similar time span. Needless to say that his internal injuries were fairly massive, but he survived nonetheless.
EDIT:
http://autospeed.com/cms/A_109806/printArticle.html
0-1018kmph (632mph) in less than 1 tenth of a second.