Smart cars can be towed 4 down as I did 300miles over the weekend with a new car picked up 12/17 and fitted with roadmaster system. Follow rules in manual brakes- parking and regular on, move gear to neutral .turn key as far left as possible, leave it in slot. release brakes, turn off non tow switch on dash - see manua, l close door and go. mileage does not register and MH did not notice it was pulling such a light vehicle.