Good idea. I agree... I want a perfect GPS history always, even if my PC was off.
However, the "blue-tooth GPS logger" device would have to stay connected to the SATs to know if it is moving or not. This could possibly require too much current to avoid dead-car-battery problems.
I think they would need to make a "blue-tooth GPS logger" with a special power-down mode and a motion detector or ignition-connection to detect when to re-power-up.
I suppose you could take apart a logger and figure out how to turn it on/off via 12v acc.