Since I am retired I don't drive very much and only fill up my tank around once a month. Well was I in for a surprise! It was almost a dollar a gallon more than the last time I went to fill it up. This made me get off of my lazy back side and put on the belly pan that I had taken off a while back to do some work under the truck. When I tested my original belly pan 4 years ago it made a 1.25 MPG improvement in gas mileage on a 160 mile round trip that I made once a week over a three month time period. The first picture is the current v.2 version that I am using now. The second picture is the original v.1 version that I made 4 years ago that I copied and pasted from another web site that I made back then. The main difference is that v.1 was one piece pan tied to the factory tin can skid plate. The v.2 is a two piece pan tied into a Mobtown front skid plate that I got to protect my Fumoto valve.
![[IMG]](/proxy.php?image=https%3A%2F%2Ftwstatic.net%2Fattachments%2Fimg_0012-jpg.3197094%2F&hash=17af9b6b8d799bab000f1585cb69e593 "[IMG]")
Almost 2 months ago I upgraded to the TRD 17 inch wheels in preparation for the Wilwood big brake kit. With slightly larger tires my MPG took a small hit so I started looking for ways to get that back. For some background I earned my commercial pilot license in 1972 but since the airlines were not hiring then I went to the Navy flight school and spent 20 years flying in the Navy. After retiring from that I changed careers but never forgot the aerodynamics that I learned. In an aeronautical engineering class I took in college I had to design and build 2 aircraft wings. One was for high speed and low drag and the other was for low speed and high lift. We had to put sensors everywhere and put them in the wind tunnel.
On the upper part of the truck the only thing that may make a small improvement is a tonneau cover which I already have. Therefore, I looked under the truck to make some improvement. I use the truck for towing once a year and hauling several times a year so I do not need skid plates for off roading. For the last 2 weeks I have been designing and building an under body pan to improve the aerodynamics. I will be driving a couple hundred miles in the next few days so I should get an idea of any improvement. I would like to put my truck in a wind tunnel but the closest one to me is at Florida State University and they want $15000 to use their facilities. That is not going to happen!
For those who off road you could put a small pan between the transmission skid and the fuel tank which could help some and it would be a lot easier than the one I designed.
Now I just have to order a high clearance rear bumper, probably CBI, and wait 4-6 months for it to come in.
