pay-as-you-drive

A story I've just read via the BBC re a new idea that's being tested.

Using GPS technology, the black boxes will be attached to a car and be able to record exactly which roads a car was driven on.
All the information is then sent back to the insurers via the little black box, using technology similar to that used by mobile phones.
Based on the information gleaned about your driving over the past month, the computer works out an itemised bill.

I'm not usually one to jump up and down about 'big brother' but the idea that my every road trip will be itemised makes me feel a little bit unsettled. Also what about those times when you've just nipped off to visit someone that perhaps your other half doesn't know about?