Without a question, this is the 4WD to have. Pricey vehicle; but the best by all means. I would have given a perfect reliability score, but a faulty passenger seat sensor that activates the air bag left me without my X5 for 29 DAYS because the spare part had to be ordered from Germany, and part number was not availble??? That said, the dealer loaned me a fantastic 530 for the whole time the X5 was in service and every day they kept me informed about the situation, with a very professional and courteous approach.
The 4.4 engine rocks!!! Lots of power all over the RPM band. The engine sounds great too. (Fuel economy is not great, but is expected from such powerful and heavy vehicle) Brakes are incredible too. The 19" wheels make the X5 look sporty and muscular.
Better sound system. Upgraded sound option not even close to the sound quality and power of the Mark Levinson system found on Lexus. No CD player when ordered with Nav, is totally out of BMW league. No iPod connector possibility with Nav and DSP is a shame!