You can try any car audio deck that includes an auxiliary input jack, but you'll need to control your tracks from the iPhone itself, and you won't get hands-free capabilities (unless the deck has Bluetooth support).

Many newer cars have iPod interface cables available, they are expensive, but hook up to your existing, stock stereo. Again though, no Bluetooth support.

Otherwise the Parrot MKi car-kit range may be worth a look? We have reviewed the MKi9200 model and it provides both music playback and hands-free Bluetooth.

Try this model from Kenwood KDC-BT7043U. I have one and it has bluetooth hands free also has usb and 3.5 socket inputs and runs my Iphone using remote supplied with radio and great sound as well.