Voluntary no. But lets get real - we all know where this is going eventually.
That's a fair point. But this is one of those corner cases where I could argue things either way with almost equal effectiveness. Whenever I come across one of these I tend to err on the side of caution and stick with "No. The Government shouldn't muck with this" but to be honest, I don't see this case as a huge issue
if proper safeguards for the data were put into effect and it was made explicit that (a) the data belongs to the owner of the vehicle and (b) consent is required for accessing it (absent a warrant to be issued only on probable cause).
Keep in mind that most newish cars have such "black boxes" already, although they currently "trigger" only when the car is involved in an accident and record data for only a few short seconds. Car companies supposedly use the data to improve the airbag deployment algorithms and other car safety systems.
I'll tell you that if the right safeguards are there (and it's possible to implement such safeguards)
I can deal with that.
Your mileage may vary.