[buggeryorkshire]

Good point. Though certainly Google Maps (through AA) lets you download the route in advance so you don't technically need data.

[maxerickson]

Depending on data quality in the area you need, one of the many apps that use OpenStreetMap data can be a good backup option. Where I am in the US it is plenty reliable enough for highway driving.

[Enginerrrd]

Yes, I'm aware. And that's my default minimum starting place which works until you realize that google maps routed you through a private gated road and you need to readjust and reroute while out of cell-range. Or a large section of the road is passable only on foot or perhaps with a quad, but certainly not even a 4wd truck. Or it's convinced that you should simply "turn left!" off a cliff numerous times.

All of which happened to me just last week here in rural CA.

[wbl]

You do when starting a trip out of service. And sadly being a T-Mobile customer that's a good chunk of CA.

[reaperducer]

Check to see if you can download more territory.

On my car, deep in the options, is a screen that shows CONUS, and lets you draw a box around the portion you want to download.

I have a box drawn around an area about twice the size of California. Hopefully your car has enough storage for that size, too.

On those occasions when I'm out of a cellular service area, the map shows a banner reading something like "No cell connection. Using downloaded maps."