Most new cars have an aux jack on the front that just works with the mini-jack for the ear buds. You still control everything on the ipod (actually you can control volume on the car or on the ipod) but the sound comes out the car speakers.
There are very few manufacturers that offer true ipod connectivity. As far as I know the only people with an ipod interface is 2010 hyundai's. By ipod interface I mean you plug the ipod in through the connection at the bottom and then everything is controlled by the car stereo, the songs and playlists will even show on the car stereo screen.
Many aftermarket stereos have the same style hookup as the new Hyundai's do. If the car you want doesn't have the connection you want, just replace the stereo for $250 and get something better than what comes stock with any car anyway.
