Thread: Best Car GPS

but...

from a phone vs incar review site....
Most apps that use 3/4G connectivity, gradually download portions of the map as you require them, to save space on your smartphone storage. Though handy, this puts you at the mercy of mobile networks which are prone to dropouts depending on your carrier and location. Drive away from an urban centre and things can become spotty. Head into a tunnel and the mobile network may die altogether. Plus If you are overseas and roaming....

Some let you download an entire map over WiFi, so you can get around without worrying about your 3/4G connection. The downside is that a country or state map will take up a large chunk of storage on your phone. Plus, while almost all GPS apps support 3/4G, far fewer give you the option to download maps for use in offline mode.