For me the idea of any kind of interface in vehicles should tend toward audio anyway. Anything that takes your attention away from the road, wether it's tactile or touchscreen is a potential distraction.

Voice control seems the obvious solution but there are probably better ideas, especially as someone who's accent confuses all but the best recognition, or well trained, software. I end up talking in an "American" accent to my car ... but then I do enjoy pretending I'm Michael Knight.