those are the "official" performances fiat claims its cars have.. trust me they are not very accurate (especially fot the petrol ones) on more than one magazine when they tested the cars the 0-62 speeds were more like:
1.6 11.3 sec
1.8 10.4 sec
2.4 8.7 sec
not sure about the diesels
there should also be slight differences between 5 and 3 door but not the 0.5 secs fiat claims