A turn-by-Turn GPS application for the iPhone, the G-Map application, already exists in the App Store. There is no monthly fee required and no internet or wi-fi connection needed. Each application (XRoad Co.’s G-Map U.S. West and G-Map U.S. East) will cost you $19.99.
MacRumors shared its review:
We briefly tested the app, and it does indeed provide turn-by-turn directions (distance countdown to each turn) by way of GPS. Local points of interest (Food, Fuel, etc.) can be found, addresses can be searched, routes can be edited, detours added, and types of roads can be avoided (highways, toll roads, etc.). If a turn is missed, the route is recalculated. The app even is said to have 3D Images of major intersections (we were unable to verify). Notably absent, however, are voice prompts to let you know when the next turn is.
However, this app looks awesome.