The standard new 500 feels really underpowered in the test driving I've done, so that's why I went with the Abarth. Not sure about top speed, but in a brief charity run at Charlotte Motor Speedway, was able to (legally) hit about 105-110 but was limited to not passing the other drivers, so I feel confident there is more top speed there.
I am thinking of doing some auto-cross SCCA this year, totally a novice, and certainly with the Abarth a bit lower than the regular 500 (and turbo etc) that puts it in a different class.
The Motori Italiani show in Charlotte was awesome, but no Xs were there when I was looking. Tons of Ferraris and Lamborghinis, a few older Alfas, and a few Fiat Spyders.