I am betting on voice. I don't think you should be looking at a screen while driving. Http://plexinlp.com is building an eyes off interface for cars (and other

I am betting on voice. I don't think you should be looking at a screen while driving. Http://plexinlp.com is building an eyes off interface for cars (and other things) to me the ui should work while looking at it or via voice. Just like conversation s with humans. They work over the phone, but they can be reinforced with visuals.