While Frank Stephenson did design the production new generation Fiat 500 it is a pity he did not mention, credit, Roberto Giollito and his Fiat Trepiùno concept car (below) which served as the inspiration. It was named for a unique 1+2 seat configuration where the front passenger seat could be slid forward, under a recessed dashboard, to create two full size passenger spaces beside the driver. Pity that didn't make production!
Still getting a concept to production largely intact, past the bean counter cuts and real-world requirements, is no mean feat. Love watching him draw too. I wondered if he'd done the Abarth variation but, from the comments, found it was the work of Ruben Wainberg, HEAD ABARTH STILE - FCA Group.