I bought my GP at just over 2 years old from a Honda dealer, with just over 12,000 miles on the clock. There were no service stamps in the book, so I got them to service it before I bought it.
As everything I'd read suggested the lack of a full service history would void the Fiat/dealer warranty, I also got a deal on a year's warranty from the Honda dealer.
However, when I needed to use this warranty a month or so after I bought the car, the Honda dealer talked to the Fiat dealer, and they said they'd honour the warranty unless it was something which may have been affected by the lack of servicing.
There was a stupid delay while the change of ownership was registered with Fiat, but it got sorted out eventually.
So, now I have a (partial?) Fiat dealer warranty for another month or so, and then a further year's warranty with the Honda garage.