Agree with everyone about the battery drain from BT - it sucks my V3 dry twice as quickly!

I don't keep my BT turned on anymore as:

1) It's annoying having to charge it twice as often
2) I don't really spend enough time on the phone in the car to warrant keeping it on
3) I'm still not convinced about the safety of BT

I usually switch it on if I need to make a call from the car. Otherwise if I pick up when it's off I just use the V3's speaker phone function.