The problem comes with older cars when the technology/data is no longer maintained. But cars are generally developed, built and maintained around much longer cycles than tech like smartphones so predicting all that is tricky.
That said I've just scrapped a 1998 car that had a retrofitted (by me) in-car 2003-vintage SatNav (designed for another model by the same manufacturer but plug-and-play) that worked extremely well. The only downside was a map with no updates since 2003, but you'd be surprised how many roads are exactly the same since then - almost all of them!
And I actually took the SatNav out and am selling it on eBay, lots of bids despite its age.
