Yeah, there is no difference between the '05 and '06 E53 X5, besides what Motordavid said that '06 was the last year of the E53. Had both a 4.4i and 4.8is E53...and they were flawless trucks, and safe!! My life was saved in my 4.4i, and in fact you can see my video/commerical on the bmwusa.com website. I am the official "safety man". The X5 has been called (my many independent groups) the safest car ever made or tested! Good Luck!