I remember the FIAT 500 very well, and saw a couple of the FIAT Arbarths racing.
Back in about 1971, my then girl friend had a '500, but she hadn't, at that time, passed her driving test. I used to take her out in it now and then, in the summer. It had a full 'Webasto' sun roof, which rolled back, and was a great help, as I could sit on a cushion, with the top of my head out of the roof - a darned sight more comfortable than being hunched over when driving !
There was also one in my neighbourhood which was used for delivering small vegetables to local businesses. It was painted silver overall, with screw heads painted at corners and panel joints. There was a large key, made from plywood, protruding from the rear engine cover, which turned as it drove along - hilarious !