We towed a 2008 Smart Passion Cabrolet for about 10,000 miles behind a 27 foot Freedom Express Class C.
We towed four down, with Evenbrake supplemental braking.
It towed very well behind the motorhome, even in the mountains. We had no problems with the Smart and were very happy with it.
There were a few tall topes ( think giant speed bumps ) in Baja Mexico where the Smart's low ground clearance caused me to worry, but we got over them easily.