Greetings,
I have not used ViewRanger as a Sat Nav for finding my way to a location, only used to record routes/tracks or to share routes via internet with others. It will work with free maps but it is best with OS maps.
I think that you have to take care not to use too many 'way points'. I have bought OS maps from Dash4it.com
There is a free OS maps app for 'phones via which you can download the latest paper map onto your Android and/or iPhone 'phone. The latest paper maps have a code on them which has to be typed into the application, not too difficult - well I figured it out
As a 'phone SatNav I use a product called "Here" which I have found comparable if not better than those systems fitted in many cars, best bits are that it is free and map updates are too
Why pay £250 for a car update, seems ludicrous to me, take a look at;
https://maps.here.com/?x=ep&map=52.9667 ... ,10,normalI have used the system on Windows and Android 'phones, it will work offline once you have downloaded the relevant maps. I have also used it on trips to France, America, Canada, and on city breaks to Prague and St Petersburg.
The HERE suite will also download travel information for bus and trains.
Hope this helps.
TTFN
Hugh.