It's quite common in investigations of plane crashes that the aircraft manufacturer is involved in the investigation and makes public statements (usually to the effect of "we've ruled out any problems with our plane... must be those darn pilots again"). The situation with cars is a bit different in that it's (usually) private individuals rather than professionals, but I'd say that the track records of car safety vs. aircraft safety definitely point towards following the model used for air crash investigations.
http://www.geek.com/mobile/toyota-acceleration-case-shows-wh...
In that case, Toyota's horrible programming practices do make it possible that the logfile doesn't fully reflect reality:
http://www.edn.com/design/automotive/4423428/Toyota-s-killer...
Should people expect any privacy with regards this data? Maybe just share it with the NTSB and allow them to issue the statement that this accident was entirely not tesla's fault?