The $99 only gets you the unit you plug in under the dash, you have to have the Garmin Nuvi 1490 unit or better.
That is the unit I have so this could be another toy I 'need'.
https://buy.garmin.com/shop/shop.do?pID=38354&ra=true

or
smartphone: Simply download the Garmin Mechanic app from the Android Market™ and follow the on-screen prompts

The Ultra gauge is a bit small and that wire is a pain in the ar$e.