This. Why doesn't Apple simply implement a "CarPlay" function on the phones screen so when you get in your car to drive it can switch over. 4-6 big buttons for common apps like Maps, Music, search, or phone, Siri is active so voice commands can be used, BT is turned on so it can interface with the car system. An option to either read texts/email to you (and reply via voice) or a function to quick reply to the sender that I am driving and can't respond right now but will shortly. Heck even add an OBD dongle to your car that can give you real time data on all your mileage, fuel, computer codes, etc.
Adding a simple bracket to your car to hold your phone is going to be much better than some hacked and expensive car stereo interface that won't receive timely updates. LifeHacker did an interesting article yesterday about the apps available to interface with OBD dongles. Surely someone can perfect that interface and make it useful? Either way, the car interface of today is hopelessly out of touch with modern tech and usefulness. All these things can be accomplished without leading to more distractions and can actually improve road attentiveness.