I towed my 2008 Passion Coupe about 500 miles behind my heavily loaded Class C motorhome almost immediately after taking delivery and getting a Roadmaster (All Terrain, I think) installed professionally by the only place I found that had already installed one on a Smart before mine. I Had no problems with the installation and afterward I followed the directions given me by the North Houston Smart dealer to the letter: (1) Position car straight behind the motorhome within reasonable reach of the hitch. (2) Set car hand brake, shift into Park. (3) Attach hitch and all appropriate attachments. (4) Inside the car, put key in position 2 without starting. (5) Apply foot brake and hold down while you shift into neutral, turn key off as far as possible [position 1-key won't come out], release foot brake, release hand brake. I had no problems and it towed so easily that I left my motorhome's rear camera on so I could feel sure the car was actually following. The car's front wheels did oscillate twice, both times when I was making a very sharp left turn in a parking lot. I stopped, slowly straightened out and drove on with no further problem. The odometer did not register the mileage (even though Smart USA originally tole me it would). To unhitch: (1) Set car hand brake. (2) Turn key to position 2 without starting the car. (3) Shift to Park. (4) Unhitch the car.
Since I was staying for a few months, I was able to simply pull pins and remove the tow bar and all noticeable towing apparatus from the car, even tucking the electric plug behind the front license plate.
Now that I'm planning to move on again, my only concern is that I remember how to put it all back! (Actually, I expect it will be almost as easy to put back as it was to take off, as long as I didn't misplace any of the pins.)