The HUD app is cool. And if you're concerned about running the battery down on the iPhone you can get a plug to go into the cigarette lighter with a USB connector on it that will keep the phone charged.

I keep my iPhone in the compartment at the aft end of the console. I have a USB connector in there that is hooked to my new Kenwood stereo. It keeps the iPhone charged and allows me to run and control the Pandora app from the radio. I'd have to give up Pandora to run the HUD so probably won't happen.