Can't tell if this is something I can add to my car, or if it's something they will make available in new cars.

New Cars only: "The integration works through the iPhone’s lightning port, meaning that it’s only compatible with iPhone 5, iPhone 5s and iPhone 5c, and of course not ever new car sold will have CarPlay integration built-in (it’ll likely be an add-on option for many of these manufacturers, since it represents a chance to offer additional value and that’s generally the way upgrade packages work)."

Source: http://techcrunch.com/2014/03/03/apples-new-carplay-system-will-turn-tens-of-millions-of-cars-into-iphone-accessories/