2wd Vs "auto" Mode

[jthelman]

So that cool knob that changes the driveline from 2wd to auto to 4wd high/low:

 

According to the manual, in 2wd it doesn't spin the front axels. This should add a bit to the MPG over "auto" mode right? Or is this splitting hairs?

 

I snickered when I first saw this knob. It's been a while since I had a truck. I remember transfer case levers to shift and hubs that needed to be locked, now it's like changing a radio station....

[Outbacker]

According to the manual, your milage will lower slightly driving in Auto as opposed to 2hi.

[redvett]

In 2wd the front axle is disengaged & in Auto its engaged and at the instant there is slippage detected the autotrac module will engage the transfer case,seamless & almost undetectable to the driver. A loss of about 1 mpg will occur in auto while driving on hard dry surfaces.