Good to see a new product that permits new options if carefully considered but let's not be making the car unsafe "just for looks!" Anytime you change springs&shocks, lower or raise the car, swap tires and wheels, etc. the handling dynamics also change.
The smart car's geometry has been engineered with considerable understeer as a safety measure. This is not, to coin a phrase, "your father's Oldsmobile".
Just a note of caution, then. Suspension geometry should be modified professionally, setting up your car with proper F/R weight distribution and carefully corner balanced for safety and the performance you require and can handle.
My 2 cts CAD