I had my tailgate off for about a year and a half, when I went to put it back on it wouldnt close properly. I talked a friend of mine at the dealership and he told that running without a tailgate will warp the sides of the bed.

 

If you are judging just from the gauge and not actual gallons at the pump, your method needs to be changed. A fuel gauge is not accurate enough to determine better MPG.

 

areas of drag ....are the rear bumper... axles ...... and the wind dam aka tail gate.... i run with it up and down and yes i do get better fuel economy with it down.. with in the last month i damaged my gate and had it off and the economy jumped even higher. I drive over a mountain pass weekly and the winds there can exceed 50 miles an hour. with my gate off i felt less drag than i felt with the gate on. i also noticed that with the gate off on the old country roads i stirred up more dust on the side of the road, with the gate on the air flow gets traped and loops back on itself. in the bed area. don't believe me put and empty soda can in the bed next to the cap drive down the freeway and watch the can do flips in the bed...take the gate off and the can just sits in the corner.

 

It seem like common sence? Tailgate up is kind of like a parachute. Tailgate down the wind blows right out the back. But hey I'm not college educated so what do I know. lol

I always have mine down on highway trips. It also helps from being jerked around when its really windy out.

 

It may not be the best way to judge MPG, but the gauge measures how much money I put in my truck (I have memorized how much it takes to fill up to an 1/8th, a quarter, a half, 3/4th, and a full tank), and thats good enough for me. Anyway not meaning to be a dick, thats not the important thing anyway. My point was that is a pretty big jump, and it made one HELL of a difference for me. What works for me may not work for you, or may not be up to your standards, but it's the perfect way for me to judge it.

 

I just read at the dealership, someone, I cant remeber who, did a windtunnel study on the subject. The verdict was that drag coeffecient is lower with the tailgate up, because a mass of air is trapped in the bed and it begins to rotate and diverts the airflow over the top. I would tend to think that lower drag means higher MPG. I'm going to trust the guys with the PHD's and a wind tunnel and run with my tailgate up.

 

Well all I know is that my truck with the tailgate down got almost a 1mpg improvement on the drive to Corvallis, Oregon to Biggs Junction. 3 trips with it up consisted of an average of 16.64 MPG and 3 trips down consisted of 17.45 average.....that is with an average speed of 72 mph all trips. for the record this is a 1993 4x4 short box standard cab f-150 with an E-4OD, 5.0L and 4:10 gears I might add.

One thing to think about......my tailgate weighs like 120 damn pounds with the diamond plate that covers the whole bedside, that can be like one small passenger......my truck also weighs 4,550 lbs with full tank of fuel (if anyone cares). So I can see where removing the tailgate could help gas mileage do too weight reduction.

 

They way I look at it they can do all of the test and studies that they want, In all of my "real world" experiance the mileage is better, doesnt matter what truck, Ive had fords and a chevy. What looks good on paper doesnt always work in the real world.

 

if your getting 17 mpg with your 5.0...wanna trade?

 

Depends on what the trade is for.......everything is for sale
I know you guys probably think I am full of BS.....but I did learn how to do math in school.....and I know my #'s are right since it was an average of 3 trips.

 

My brother-in-law drives a 01 Dodge Ram 1500 and he gets better mpg's with his tailgate down. I drive an 88 F-250 and i also get better mpg's with my tailagte down as well.

 

They did a study and found that the gas mileage is better with the tailgate up.

 

That is my point. With it up the wind has less surface area to contact because an air "dome" is created with it up. But either way I've tried it up or down and it doesn't matter squat for mileage. I'm not sure how everyone's comparisons are being done. Was the temp. the exact same both tries, how about wind, etc.

 

Are these the same guys with the PHD's running the economy and creating peace and harmony throughout the world?

I know that the tailgate up uses more gas, just look at the NASAR trucks they have a fin on the back that provides downforce and at the same time it makes a bigger hole in the air causing them to go slower

 

Simple question: If leaving the tailgate down is better for mileage and better airflow out the back, why would a truck, such as the Lightning, who's sole purpose is to go fast and not worry about anything falling out of the back, have a tailgate? If it were so detrimental to the airflow of the truck, why wouldn't the Ford engineers have decided that it is better to just put a net or other similar device in?