Originally Posted by
msb0b
Factory-installed automotive navigation systems may receive speed and steering input to continue estimate your location when GPS signals are not available. This feature is called dead reckoning. You can also achieve the same result with accelerometers.
My car has this - it gets confused by certain types of automated parking here in Japan. The worst is the type where you drive your car straight into the machine, onto a pallet. The machine then whisks the pallet up and stores it away. When you retrieve the car, the pallet arrives back turned through 180 degrees so you can drive straight out.
Of course, the whole rotation of the pallet happens when the car is turned off... so the navi thinks you're driving in completely the opposite direction until it manages to get a good GPS fix and reset itself.