Cell phones and driving

They put the silliest stuff in newspapers. Today's has a report that talking on cell phones causes us all to drive more slowly, making the daily commute to work take longer. The guy who did this is in Utah, where maybe monster traffic jams are not the number-one problem, and the amount of slow-down mentioned is 2mph. So exactly how much does going 87mph instead of 89 impact (sorry 'bout that word) a morning hurtle from the Atlanta airport to Norcross?