I don't have the NAV in my 05 4WD FEH(I bought it used). I do use a ScanGauge & find it a very useful tool(although I wish it read SOC)

There is NO WAY I would pay $2000 for the primitive DVD based NAV option myself(I use a Garmin 2620 GPS). I would like to have the hybrid display the NAV gives you just because it is cool, but it's not worth $2K IMHO.

I average 33-34 mpg with mine & it's 4WD, I doubt adding the NAV display would increase my mpg enough to worry about.

I upgraded my sound system significantly myself & it blows away even the high end FORD options by a significant margin. I used to sell/install high end car stereo & I am not at all impressed with the FORD "premium stereo"

~John