Your car's data protected by 4th Amendment, 18th Amendment still valid while driving
Did you really try to stop for that big, red sign or did you miss it and plow right into a bus full of kids clutching their DSs? This is the sort of question that can be answered by some automotive event data recorders, EDRs or black boxes that manufacturers might read later to get more information about crash severity and causes. In one California case, State v. Xinos, that data was used to reconstruct a crash and achieve a vehicular manslaughter conviction, showing that George Constantine Xinos fled the scene of a crime. However, an appellate court later determined that data to be inadmissible:
While a person's driving on public roads is observable, that highly precise, digital data is not being exposed to public view or being conveyed to anyone else... We conclude that a motorist's subjective and reasonable expectation of privacy with regard to her or his own vehicle encompasses the digital data held in the vehicle's SDM.
So, the vehicular manslaughter conviction was overturned -- but he's still on the hook for failing to stop at the scene of an accident, DUI, and causing an injury while drunk.

Nokia Plan B was just a hoax all along