Actually all of the devices are supposed to turn off when the car is moving, however you can get devices that are supposed to be fitted in the back of the car that stay on when the car is in motion. Sometimes you see these fitted in the front so that the driver can see them too.
Anyone who has spent anytime driving in Japan will know that it\'s not important for the driver to watch where they are going but to know where they are going to go and where the nearest convenience store is.
Most of the in-car navi system are actually pretty usefull - especially finding your way around a city like Tokyo or Osaka where most of the streets were laid out seemingly at random. It\'s really cool to be driving along and have a voice (your choice of male or female) tell you very politely that you need to be in the right lane so that you can turn at the next intersection in 300, 200, 100, 50, 40, 30, 20, 10 meters.
Stu
