HI,
Having just collected my 500 i asked the salesman would he recommend the Fiat sat nav, he was very clear with his answer, NO! 'Its rubbish buy a TomTom'
You can buy a TomTom One QI from Amazon for £114 delivered next day, its a very good Sat Nav and you can move from car to car as others have mentioned. Plus you have regular map and other updates.