The harsh reality is that FIAT stuck a badge on it so you'd pay more for it.
For example....Performance wise whats the difference between a Punto HGT and Punto HGT "ABARTH"? What makes it special?
Surely if someone bought a Punto HGT, then the "Abarth" kit and all the mods it would be the same. Therefore the reality if there is no performance difference. FIAT should have made the ABARTHs something much more special and in the face of commercialism saw the lira signs and didnt. Shame.
Im sure the stilo is a very nice car dont take it personally, Im not saying it isnt...just that there is no real difference between some of the Abarth models in the FIAT range, especially concidering what Abarth stood for originally in years gone by.
Personally I own a Lancia Delta Integrale Evolution which is not an abarth but is a rather special car in its own right and believe me I know what real performance means.