I did a few searches in this forum to see if there were any posts on towing an ML350 4 down and could not find one. Anyone out there doing it and if yes what equipment are you using ?
Congrats on the HHR...that's what we tow and we love it. Very comfortable, economical, and if you drop the rear seats (front pass seat too!) you get tons of cargo space. You can haul 8' lumber, if you need to :)
Don't forget to pull the fuse per the owner's manual, or you'll end up with a dead battery. Some folks replace the fuse with a switch that has a fuse in-line, saves from having to pop the panel and pull/insert the fuse.