Do dead reckoning with the accelerometer, phone home with your speed later. Or just look at the endpoints of the trip when you take it out of the Faraday bag an

Do dead reckoning with the accelerometer, phone home with your speed later. Or just look at the endpoints of the trip when you take it out of the Faraday bag and calculate average velocity. Or don't try to enforce speed limits through phones, because that doesn't make any sense anyway. Require GPS-enabled governors in all car computers.