[rdefayette]

Originally Posted by aerohead

For a back of the envelope calculation,if your mpg was 17.53,and went up to 18.93,that's a 7.98% mpg improvement.That would suggest about a 15.97% drag reduction.If starting at Cd 0.41,your 'Wedge" would put you in the neighborhood of Cd 0.344.
Not too shabby for a single mod! And you probably saved at least 300 man-hours in fabrication time versus an 'ideal' cap.
I like it! Thanks for doing it and sharing the data.

Thanks,
your calcs for improvement are pretty much spot on for what I gained (difference) in mpg.
When I bought the truck I was getting 13.6 mpg so overall I'm happy with where it was to where it is.
Like everyone knows though the first big improvement numbers are the easiest, once you get down to the final "small" improvements it can be rather difficult.
Just like in racing taking the first steps for weight reduction are easy it's the last 20#'s that are a pain.