Fiat is set to debut the high performance version of its fashionable 500 -- possibly in October at the Paris Motor Show -- and spy shots have revealed that development is well underway. If fans of the retro-mobile were let down by the Abarth model's relatively puny 133-horsepower and sub-eight-second run to 60, the SS model will improve those numbers considerably. For its range-topping city car, Fiat is likely to fit a revised turbocharged engine offering an estimated 160 horses along with the Q2 Torsen C limited slip differential from Alfa Romeo.