I have been towing since April 2014 with my 2008 ML 320 CDI (same as 350 bluetec). 6000kms so far. 2014 Traile Lite Trek 27 Bhs. 27 ft, 5400 lbs empty, 6000 with a lot of gear, no water. If I carry a full water load I am illegal. While having more than enough power (long, steep hills in British Columbia Rockies), good crosswind stability, I would recommend everybody who is considering this kind of combination NOT to exceed the tongue weight rating and Gross Weight Rating. Also, watch the rear axle rating. Weight distribution helps but does nor make it legal in case of a crash. DOT will only look at the posted numbers on your door sticker and vehicle/trailer manual. Also, the Wd helps but puts more strain on the hitch, and the Ml. I am a class one driver, used to drive semis for work and if I was to choose I would have gotten a little bit smaller one or with a lower tongue weight. This one is at 675 pounds. I keep the propane tanks inside on the axle, I load everything in the rear of the trailer to stay legal. With a full tank of diesel (90 litres), wife and two toddlers I am right at the limit. I always fill with water close to the final destination and fear a DOT checkstop. On the other hand I get 16-18 mpg with this big box behind, off roading is awesome, and trips are far more comfortable than with any truck. I would change only for a Ram Ecodiesel with air suspension:). Anyway, I hope this helps. Hills are not nearly as bad as winds as we have in crappy weather Alberta. The ML is an awesome beast for towing as long as you stay legal. The 3.0 simply blows Hemis for relaxed, long distance towing. I rarely rev over 3000 rpm in any situation. The GL is even better, more stable in crosswinds. Good luck! (Will post pictures).
