My wife's new-to-her 2011 Hyundai Elantra connects perfectly fine with my iPhone 4 and will pick up the phone and play music through the car's audio system. But there's absolutely no ability to control the playback from the car's controls. There's supposed to be, but it simply doesn't work.

BT has a lot of promise, but I can't think of a single product or combination of products where you can see it all come together like you'd infer from its specs on paper.