In snopes.com the story is headlined:
Claim: While a teenager, future First Lady Laura Bush caused the death of a classmate in a car accident.
Status: True
http://www.snopes.com/politics/bush/laura.asp
But if you look at the details of the case as described in this article and elsewhere, it seems very likely that she had every intention of killing the victim, making this not just an accident, but a cold blooded murder. What do you guys think?