I've actually wanted this for my car too... I've thought for several years, if there was a near-field really high speed bluetooth style interface that was similar to chromecast + touch... basically your screen in your car, when your phone is docked (near) the system will now yeild control to your phone... calls, audio, video, touch are all interfaces in the car, for the phone.

The same could be done for a desktop-like computing environment... for that matter a laptop shell... just a battery, screen, keyboard, trackpad that your phone controls.

We're really at a point where this should be doable and eminent... if say Tesla and Apple could get together on this (with very liberal licensing for other companies, as long as they meet the full spec) would be the most likely chance of this getting out there and succeeding.