An earlier study conducted in 2006 found that motorists who drove while talking on cell phones - either handheld or hands-free - were more likely to be involved in a rear-end collision than motorists who had an alcohol concentration of .08. Researchers believe that motorists talking on cell phones miss up to 50% of the visual cues that a non-talking driver sees.
None of this is to suggest that one get hosed and get behind the wheel of a car. The larger point seems to be that with every new device we put in a car we create more distraction for drivers. It is that distraction, whether caused by electronic devices or alcohol, that makes driving more hazardous.