I own a 5 series (E60) with aftermarket nav (TomTom910), and an X5 (E70) with built in Nav.

Although I like the neatness of the built in nav, I have to say that in terms of usability and functionality, it is absolutely crap. No points of interest, no 7 digit postcode, no street level road names (only "major" roads), its PAINFULLY slow at calculating routes. Compare this to the TomTom, full worldwide maps with full postcode, every street name, very very fast, points of interest including speed camera alerts (updated monthly), ability to change voices, display options, etc etc etc. The list just goes on and on.

I agree that people in the UK would not want an X5 without Satnav. BUT, 95% would probably want this satnav to be a TomTom and not the built in crap outdated rip off satnav that BMW are still selling.

If I were to buy a 2nd hand BMW, I wouldn't bother to see if it had satnav or not. I'd fit a TomTom regardless even if it did have it built in. When I buy a new car, I always trade my old ones in, so options make hardly any difference to the sale price at all. If you sell your cars privately, then it would probably make sense to pick some of the more obvious options such as satnav.