Ford 6.2 gas vs 7.3 gas highway gas milage

deltabravo wrote:

...unless the DW is driving.

For decades we've been driving 560 miles route between San Francisco and Las Vegas, often splitting the drive with DW.
We both drove at the same cruising speed, yet DW was making better mpg.
Slower acceleration, less aggressive passing did make noticeable difference in overall mpg.
Than I was coming to the destination 20 minutes faster.