During the very early stages of the smart's development, there used to be a controversy in Europe about how often the car would flip in sharp turns. It took some doing to get a compromise deemed safe enough to be put on the market and on the roads. That happened to be the 450.
The decision to adapt the car for the US, with the help on new technology, produced the 451.
To alter the balance that Engineers fine tuned over years of research and efforts may
compromise its behavior; not to mention
release the manufacturer from its warranty responsibilities.
Beware!
Not just my observation, but a note from Smartville... (as per a conversation with O. Amélineau, smart Media &
PR Representative, Daimler France).