What I find is that if, when I turn off the car, the map was not being displayed, when I turn the car back on, the input destination screen will be what is displayed instead of the map when I switch to NAV again. However, if the map was being displayed when I turn off the car, upon the car being turned back on the map will be displayed. It works that way for both v29 and V31.

As an example, just like the original poster, I always have the map displayed. When I turn off the car and turn the car back on, it goes back to display the MAP. However, if I switched to MENU or I had my telephone contact list displayed etc. before I turned off the car, when the car is turned back on, the MENU or the telephone contact list will again be displayed, respectively. When I switch the display to NAV, then it is the input destination screen that is displayed instead of the MAP. To have the MAP be displayed again, I have to scroll down to the MAP option and select it and then it'll be displayed.