An interesting report on the findings of a very involved set of tests. I have to say though that I find some of the test scenarios a little unrealistic (Conditions and Tasks in Table 1). 

For example who is ever going to be expected to do verbal puzzles involving numerical reasoning over the phone while driving or recall a sentence word for word? If I received a call while driving it would never be about anything so involved. Similarly I could never envisage a time when I would want or need to manually tune a radio while driving. Every car radio has presets these days, there is just no need. Any of the other control features used in the test are everyday movements that we do automatically on a day to day basis, I never have to take my eyes off the road to turn on the heater or alter the fan speed or change the volume on the radio.

I think the road layouts were a little too simple to represent everyday conditions too. You never know what position you might be in or what conditions you might have to deal with when you receive a call but there were no junctions, roundabouts or traffic signals to contend with in the tests. Nor any adverse weather conditions.  

The question and answer session  was enlightening (Section 4.2.3). Unbelievable that some people admit to having business conversations while driving and some admit to their calls lasting for 20 minutes.