This is an interesting question, and something I have though about since deciding to buy a '08 before the year ends.

I currently have a low mileage E46 M3 that I did not buy the extended warranty on due to the low mileage on the car, and the way I was using it – basically a weekend toy.

When I test drove the X5 about a month ago, I have to be honest, the level of technology in this car scared the sh!t out of me from the standpoint of long term ownership. The amount of electronics in these cars keeps increasing exponentially, and frankly, and I imagine owing something like this out of warranty or long-term, could get pricy rather quickly.

So, I have not personally decided what to do – basically because this will be another toy, a low mileage weekend / trip car. But if this were a daily driver for me or my wife, something we planned to drive with the frequency you are talking about, I would personally buy the extended warranty, it would only take a few sensor failures for it to pay for itself.

Good Luck
KEF