With the NAV many things are controlled and programmed directly on the screen. This is much easier than using the radio tuner button when you have only the basic radio. Also the items that have been programmed "on" are lit up so you see immediately what your settings are. There is a 136-page manual that covers this. It can be found at http://www.mygmlink.com/pdf/go2conte...k05sts_nav.pdf