Well I can confirm that all vehicles manufactured in Europe after 2002 do have something comparable to a "black box", recording all sorts of engine parameters which can subsequently be downloaded for analysis.

I used to worry that all this data could be used to track us, but then I realized how inefficient the government is.

Yeah, now your privacy will only get invaded if the government actively decides to cast their eye your way. The downside is that being chosen for a look is enough to convince your fellow citizens that invading your privacy is a special case that doesn't erode their rights, plus if the government is interested in tracking you, it might be dangerous not to let them.

And of course the "inefficiency" of government only helps until they reach a certain level of technological sophistication, which doesn't leave us much time even if you assume they're ten years behind the private sector.

I've heard of trucks being equipped with black boxes to ensure that employees aren't slacking off on the job, but that's the 1st I've heard about cars. Wouldn't surprise me though.

As far as I know the black box in your car just holds onto the data immediately before a crash. That said, the police can pretty much timestamp your every movement using EZ Pass.

I'm talking in addition to the OBD systems. This one can also record telemetry (steering angle, wheel slip, etc.).