Weights and aerodynamics - where do I post and query?

In the 10 plus years I have been reading RV and Tow Vehicle related forums the folks who post the results of changes they have made to improve MPG, the improvement has been small. 1-5 increase in MPG after spending up to $2500 in aero or engine or trans or a combo of improvements doesn't impress me.

The one thing RV'ers have done that improves gas mileage and is free is to slow down. Instead of doing 70MPH do 55 or 60MPH. It's much safer as well.