GiSTEQ sells a GPS data recorder called the TripBook that is powered by a car's cig lighter. The magic is in the software that figures out the distances. Just to see, I tried to get Linux to talk to it. It did, and it worked as a GPS, spitting out NMEA sentences.
To get it working on Linux, I had to execute the following:
stty -F /dev/ttyUSB0 38400
That just set the baud rate a bit lower than the default. The device uses a serial-to-USB converter, and Linux maps this to /dev/ttyUSBnn.
To use the GPS with any Linux software, you install the gpsd daemon. It adapts several different kinds of GPSs, producing a consistent output stream over TCP/IP. The GPS software reads the output stream and maps your position.
Presumably, the device goes into logging mode when it's plugged into the charger and lacks a data connection.
It's not clear to me how to extract the recorded data (aside from the included Windows software). Perhaps it can replay the data as an NMEA stream.
Other GPSs expose the data as a file, and the GPS appears on the computer like a flash drive.