Check out AutoBUG! The AutoBUG combines the BUG's hardware and connectivity (GPS, GSM, accelerometer, etc.) with data from a car via its CAN BUS. This system turns the car into a hotspot node on a network. The current iteration of this project should run on any GEN 2 Prius, which is one of the most fun and hackable cars around. See Brian's wiki info for some advice on how this project could be modified to run on other cars.