An anonymous reader points out an article about touchscreen dash interfaces in cars (in particular Cadillac's "CUE" interface). From the article: "I do not recall anyone ever complaining about the iOS interface and there have been plenty of attempts to replicate the experience and its flow of control. ... As simple as iOS may appear on the surface, it is incredibly well-executed balance that matches the requirements of a touch interface for phones, tablets and other horizontal screen devices. Changing the user scenario, hardware, or software will alter the requirements for the desired user experience as well. ... CUE is not as transparent in its usage as, for example, the iPhone. We are used to certain buttons that are located on the dash – sliders and dials that we expect in places that we can quickly memorize. In the end, you want to be able to reach for such a button without taking your eyes off the road. There are no such buttons on the XTS dash. Instead, there are some capacitive touch buttons for basic climate controls, audio volume and seat heating/cooling. Since the buttons are activated by touch, they feel the same."
A touchscreen UI for some functions sounds perfectly sane (how do I set the clock again?), but ditching all of the dash buttons sounds like a recipe for disaster. I've heard from iPod users (and my own experience with my long-dead Neuros echos) that the click wheel was easy to use blindly; the move to a touchscreen made it impossible to use without looking at it.