Join Date: Jun 2005
My Motorhome: Hymer 504 B Class
Thanked 12 Times in 12 Posts
The difference being seen between speedo and satnav is the same as I had on my 2005 Fiat 2.8. I seem to recall that before I sold it in 2013, it had a recall which was something to do with the binnacle [I might be wrong about the cause of the recall]. After that, the difference was 70mph on satnav, 63/64mph on speedo.
On a flat motorway, my 2013 Fiat 130 speedo shows 60mph and the satnav 56mph.
I'd say that the satnav is more accurate but not necessarily consistently accurate whereas the speedo is never accurate. I rely on the speedo to keep me within speed limits.