Update: Since posting our question, we bought a 2013 Smart Car and put on a Blue Ox base plate that attaches to our Ready Brake tow bar. Just got everything installed and working. Testing out now. Haven't gone on any long trips yet. Thanks for your responses and discussion. We will keep you posted on our progress.
Hi Vagabon, I have been towing a Smart Car (2015) since november 2015. I am flat towing it behind an Axis 24.1 (2015). I have been driving for more than 14,000 miles so far without any issues. I have the Blue Ox Aventa LX towing bars and I have the Blue Ox Patriot BRK2012 Braking system which is needed in many states and canadian provinces. I purchased the Smart Car because it could flat towed (all the steps are written in the Smart Car Owner's Manual) and also because of its light weight (1852pounds). I also installed the light wiring kit (diodes) on the brake lights. I never had issues towing it, some people use a bungee cord in the steering wheels on some older models, but the 2015 does not seem to need it. Very stable, easy to tow, you won't even notice it. To have peace of mind, I installed Tire Pressure Monitoring System sensors on the wheels, they are manufactured by EEZ RV Products, so the motorhome and the Smart Car are monitored when on the road. I also got a spare tire for the Smart Car since the size of these tires are not always available at tire shops.