I've often wondered if our trucks would do good with either a skirt or belly pan to improve airflow.

 

I was just thinking of that earlier...why not hang some sheets of plywood under the truck to completely cover the underbelly, assuming the exhaust won't set it ablaze during regens.

The bottom of my wife's Lexus looks like the bottom of a boat. I think that was done not only for aerodynamics, but also road noise reduction. If I took the wheels off, I could probably tow it around like a sled in the snow.