I have the III and prefer my Garmin GPS to the Nav System in the Prius v. Plus the Nav System being at a lower point visually ( for me ) is distracting...tried just listening to the commands, but apparently I am a visual person and need to see the map for best results...lol
I have a Prius v Three...Added a Homelink Mirror with Auto Dim and Compass....Works Great! Prius v Three Homelink Mirror Install w/Pics! | PriusChat -M
Ed you should be asking in Gen 3 forum, since we are v owners, it is possible that none of us know where the compass is on your model.
You can determine direction with the 2D North option but the better way would be to install a new rear view mirror as indicated in post 22 above and further explained in his pdf: https://dl.dropboxusercontent.com/u/3541607/HomelinkInstall1.pdf You also get an autodimming mirror which is worth the trouble by itself. It you are not up to installing, most audio guys could do it quickly.
There are numerous smartphone apps that provide a compass - at least for Android and iPhone Our cars have compasses but whenever I'm in our cars I'm charging my Android phone and running the free iBolt Dock 'n Drive (from Google Play) which I start with an NFC tag. All five application screens in Dock 'n Drive display a small speedometer with the direction of travel under it. Tapping the small speedometer displays a screen that contains a large speedometer surrounded by a compass. We use iOttie phone holders in our vehicles - they will stick to just about anything. Here is a shot of my phone in our Prius v showing one of the five Dock 'n Drive application screens. The compass reading under the speedometer on this screen initializes when the car starts moving.
One don't need a compass or North Indicating Icon to tell U where U heading. U can set navi to show North Up, from there you can tell where U are heading. Takes some thinking