What do I need to know - smart car- toy hauler

One of the challenges you will face is most of the "Smart" cars have low ground clearance. So the ramp angle is a problem for some, many street motorcycles have the same challenge. What happens is as your front end goes up the ramp the rear end drags on the ground. You can add extra ramps to lessen the approach angle.

As already shared weight limits of some ramps and the garage are other factors.