I'm using this for my 2007 Jeep and works great. I've seen it run on a 2011 Jeep Compass.
Works on Android phones... cost 3.95. Uses the Elm327 bluetooth adapter that you can get for cheap on eBay (like $18).
Here is the web site.... www.drive02.com
Also if you don't have an android phone:
This is what I did for my neighbor.. search ebay for android phone "bad esn" 2.1 ,where you can't use the phone service but you can use the wifi to download the app from the android marketplace and use it on the phone (no monthly fee). Try to avoid AT&T bad esn because some block the marketplace for some reason.