I was thinking about this today. At the bar. Drinking.
Here's another idea to help imrpove the gsa milaege.
First, reroute your heating/AC ducts outside the cab. Then, run them to the air intake for the airbox.
When driving, turn the AC on high. It will act as a superduper cold air intake. Also, since you are using the fan from the HVAC, it will act as a RAM AIR INTAKE. This is like a cheap supercharger. The extra power from the super cold ram air intake will boost HP, reducing the amount of effort required to move the truck. As long as you are careful on the throttle, this extra power will result in more gas mileage (less power required to move as fast). Isn't math fun????
