^^^ I don't disagree with you 100%, but note this:
1. Why do people always assume the driver is the only one who is going to be using the carputer? My wife uses it a lot!
2. Why people assume that the more complex interactions of the driver with the computer happens when the car is moving, and hence "dangerous"?
Remember most OEM Navs are locked when the car moves, and still, people buy them and use them. They simply stop the car, or use them at traffic lights, or hack the thing and let the passenger (YES, some people drive with passengers! :lol:) use them even when moving!
also, one finger vs 2 or more is no more dangerous. in fact, you could make better use of gestures with multitouch so that a driver doesn't have to perform repeated screen presses on a specific control to perform an action. it would also clear up some screen real estate by removing unneeded controls.