I highly doubt that this post is going to help you, but I'll write it anyway (I've been fighting the urge for about 10 minutes now).
I heard a story on 20/20 or some other crappy news program, where this dude got the book thrown at him because his car made a liar out of him. The airbag system in his car (it was a late model Vet) kept a record of the vehicle's speed just prior to the bag deploying. In this case, the dude was trying to say that he was cruising around 50mph, but his car said bull sh*t, you were doing well over a 100.
So if for some reason you needed to prove how fast you were going when you hit that stupid as*, MAYBE you can. I doubt if our cars are that technically advanced.
