Before the advent of mobile devices with 3G and WiFi connectivity, all GPS navigation devices kept all of the maps needed stored in on-board memory. The upside of on-board storage is that every map for the covered region (most mapsets include a large area, such as all of the U.S. and Canada) is always with you as you travel.
There are downsides, however. Stored mapsets become outdated, and must be updated by the user, preferably yearly. Another downside is cost. New mapsets can cost $70 or more. Another disadvantage is that on-board complete mapsets use memory - as much as 2 gigabytes or more.
The iPhone and other smartphones, and connected portable devices such as the iPad, changed this scenario. iPhone app makers produced turn-by-turn navigation apps that download needed maps "on-the-fly," conserving memory storage, and keeping maps automatically updated to the latest version in a "download as needed" mode.
The downside of maps downloaded on-the-fly is that map loading can become slow or non-functional in areas outside of 3G range or in areas of spotty cellular coverage. Those times could be when you need your maps the most.
Your decision on map type may come down to where you travel. For example, I prefer on-board stored maps, because I frequently travel in rural areas with poor cellular coverage and no 3G. However, if you rarely venture beyond good coverage, on-the-fly maps may be fine for you.
Let the chart below (apps are listed in alphabetical order) serve as your guide to map types for iPhone and other smartphone apps. When an app stores all of its maps on-board, the amount of required memory is indicated in gigabytes (GB).
iPhone Turn-by-turn Navigation App Map Features
|App||Price||On-the-fly||All in Memory||Caching Option|
|CoPilot Live North America||$19.99||No||Yes 1.33GB||No|
|Gokivo GPS Navigator||$4.99/mo.||Yes||No||No|
|MotionX GPS Drive||$0.99||Yes||No||Yes|
|Navigon MobileNavigator||$49.99||No||Yes: 1.46GB||No|
|NDrive USA||$32.99||No||Yes: 1.53GB||No|
|TomTom USA||$59.99||No||Yes: 1.27GB||No|