Unless a catalog of Abarth bits are fitted, a standard Fiat 500 will never be “quick”. Adding a 70hp Subaru boxer four, however, will help matters immensely. Apparently this swap is somewhat common in the UK, so it’s not completely unheard of.
This Cinquecento looks to have been nicely prepared, and doesn’t seem to need anything. The extra power should make it livable on the freeway, too, and surprising to anyone that’s encountered an original 500.
It’s on eBay in Florida with reserve not yet met.