[Maker]

Originally Posted by Altavia

The onboard maps have helped me a few times in areas with no cell service.

Google Maps has a feature to download their map data for any area you want. Then it does not need any cell data service to function.
Will always work anywhere you have maps for that area downloaded. I have all of FL for the very rare instance there is no cell service where I might be. When I travel out of state, I download a large area along my route if I drive, and for the destination if I fly. Fantastic for mountainous areas and national parks. Plus it functions faster for searching or browsing the maps.

Need to limit cell data usage?
App can be set to only use wifi - never use any cell data. Maps can be set to auto-update (via wifi) to always remain current. Download once and forget about it - will always be there just in case of a cell system outage disrupting your trip.
If someone has a minimal data service limit, this avoids wasting data bytes and incurring overage costs or hitting a throttle trigger restriction.
Also, when traveling out of the country, many cell plans have very expensive roaming data charges. That avoids those costs.

Waze, the nav app preferred by many people (me included), does not directly support downloading maps. However, if you first set up a destination route, it will gather roads and routing info for that trip, in case cell data is not available along the way. Not ideal, but at least something better than being lost.