It's a terrible design. A Scandinavian auto magazine that I can't recall the name of did a test this year, and found that touch screens are across-the-board more distracting than physical pushbuttons. Which is obvious to anyone who's ever driven a car and used touchscreen buttons, but sometimes it's nice to have hard figures to back up the obvious.
“Alert! Tap this little region of a touch screen now or else your map will be replaced with a route that you’ve had no opportunity to review.”
As an infrequent car user (hence the map; I know bike routes well) I am usually fully preoccupied with just trying not to die.