So, what
@BMW RT Pilot wrote is what I did for a couple of extensive trips here stateside.
The crux of the issue is...w
hat Google Maps might have for a route may not match the data your GPS is trying to use to route.
Thus, we have a very convoluted, complex situation in order to have *both* Google Maps *and* whatever GPS you're using to match routes. This is the ideal case, however, if your GPS (...SatNav...
) has your base route, and the phone routing with Google Maps has your traffic data, now you see the issue.
The best routing maybe your base route, it might turn into an alternate that Google Maps (or Waze, or...) has figured out is a better route from a time management perspective.
My route planning was Google Maps, translated into BC, which then allowed my crusty ol' GPS on my motorcycle to have a route plotted.