I did this upgrade myself a couple of months ago. It's not that difficult if you're willing to do it yourself. The hybrid info requires that you buy the M/S-CAN to ACP module, which lists for about $130 from Ford. The new wiring harness will have the wiring for that, as well as for the CD changer and subwoofer. Adding the subwoofer, though, requires replacing a major harness on the right side of the vehicle, and the harness lists for about $350.

And yes, you will still have your average econ display in the instrument cluster to go along with the nav mileage display. The instrument cluster is more accurate, as it appears to retain a tank's worth of data.

If you get the new ScanGauge, you can have tons of battery and hybrid info displayed in digital format. It is much, much more useful than the nav unit, and much cheaper.