Yes, distraction.gov has some research you might be interested in, based on studies of actual car crashes. Note that the key point is distraction, not necessarily touchscreens by themselves. The problem is that it's impossible to use a touchscreen without looking at it, which means you're not looking at the road, and are thus distracted. NHTSA basically says that if it takes more than a single quick glance to perform an action, it's dangerous. This is why most OEMs lock out the touch screen controls while the car is in motion.