I tow a ski boat with my 2011 X35d and it doesn't break a sweat with it. Up hills it just flat hauls butt. With my V8 X5 I had it did a great job of pulling the boat as well, it was just a higher RPM experience in that versus the Diesel which obviously is lower RPM/high torque and much more enjoyable experience; plus mileage while towing still infinitely better than the V8 ever was. Again, seat of your pants experience is the key as mentioned before.

I'd not hesitate pulling the travel trailer either. If I had the $ an X5M would be quite fun as well...

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2007 328i Sport, Monaco Blue
2011 X35D - sold -Space Grey
2004 X5 4.4i - sold - Kalahari Beige
2001 X5 3.0i - sold - Pearl Beige
2006 325i Sport, Sonora Beige
2000 323i - sold - Sienna Red