Drive around the world with a rally co-driver sat next to you. Simply enter your route, or open a GPX track, and get rally-style instructions from your phone. The pacenotes follow a 1-6 system, where 1 is a very tight corner and 6 is a very wide corner.
No need to prepare your pacenotes in advance, as Rally SatNav will generate them on the fly.
What it does is very simple: Just like any navigation, you can enter your starting point and destination, and it will calculate the route between the two points (GPX tracks are supported as well). However, when it calculates the route, it will show and say the corners using a simplified Jemba Inertia Notes System (basically Left/Right 6 to 1, where 6 is wide and 1 is tight). It will connect consecutive corners (for example "Left 4 tightens 60 left 3 into right 3 200").