Mom has all the fancy gizmos in her car.
So, I was driving with her a few weeks ago (I was driving her car), and she decided to program in the nav system. NOTHING WORKED. We had had this problem before too.

After getting to our lunch spot, I decided to look at it, and it was very straight-forward. Everything worked for me.

It turns out that the Nav system has a lock-out feature that you can't reprogram it while driving. Not even the passenger can change it. She had never noticed that before, because when she drives her own car, she always stops before updating the Nav system.

Anyway, it makes some sense, I suppose. I never liked to take my eyes off the road to use it anyway.

As far as cell phones, prudence would seem wisest. One could use a text to speech interface, but in that case, why not just talk on the phone (hands-free, of course).

I have been on straight, rural freeways in low traffic where checking an e-mail just didn't seem to make much difference.