I have two weimaraners (95 and 85 pounds). They ride in the back with the seats folded down. Even that is kind of small for them. I wouldn't ake them any long distance in it. I like the idea of the trailer. Two crates of any size will not fit in the X5. Plus taking the crates in and out will do lots more damage than the dogs will... probably. There's plenty of room in the back of my Yukon and in the back of my ext cab GMC pickup with the seat folded up. GM is offering great deals on 2008 Yukons until 1/5/08... and probably after. They are $8000 to $10000 off. They are very nice trucks, and I guarantee they will be in the shop less than your X5. I speak from experience.