compasses & vehicles don't mix (Score 1)

Be very careful using compasses anywhere near steel objects, like vehicles. Steel objects acquire the earth's magnetic field orientation when left stationary for any length of time, so you need to get far away from them when using a compass or your direction reading will be skewed. Digital compasses that are MOUNTED in vehicles CAN work beacuse they have a calibration routine that subtracts the field given off by the vehicle- at least until they are parked for a long period of time. Then they need to be recalibrated. In other words, don't use a hand-held compass in or within 2 meters of a vehicle. You'll get lost.