Optional TV function i believe only works in Europe to view DVD's. Doesn't work on US spec navi. As for normal operation, you can have any of the following on your screen:
1) map of your current location (in real time...updates as you move)
2) radio station number and call letters (RDS)
3) on-board computer display (consumption, temp, time, etc)
4) navi instructions
or a combo of 2+3, 1+4 at the same time; or 1, then swithcing to 2 when you change stations, then back to 1