Fiat call it City Brake Control on their UK website - it's meant to brake automatically if you are about to hit something at speeds of less than 30kph. Meant to, but I saw a Volvo demonstration of something similar - good viewing but it didn't work!!
Don't know where the phrase city stop came from - it confused me too for a minute. It's Start & Stop and I can confirm that is definitely on the t/a 4x4 as I drove it yesterday.
Ah yes the Volvo one which someone forgot to activate before hand. Lol.
I think city brake is a stupid name IMO. Emergency coliseum avoidance or something with a much more serious name would be better suited for a system which is for emergency use only and not something to be relied upon.