I'm not sure if it was on this site or another, but I read on there (not in a forum) that tailgate down = better gas mileage is a MYTH. Is that right? That just doesn't make sense to me. It would seem there'd be considerably less drag with it down. Any ideas???

 

The theory is that with the gate up, a 'bubble' of air is trapped in the bed, and the air flowing over the cab passes over the bubble and beyond the tailgate.

A bed cover or a shell reportedly will increase fuel mileage. It seems like having the gate up is not as effective as a bed cover or shell, but might work better than the gate down.

In my expeirence, I have never been able to tell if I got better mileage with it up or down, so I leave it up.

 

Leaving the tailgate down creates more turbulence (airflow travelling in different directions). Turbulence creates drag. If you don't believe it, throw a whiffle ball through the air and see how quickly the turbulence slows it down.

This subject gets bashed about about once a month.

 

Personally, I hate it when the tail gate starts bouncing around so I keep mine up. My brother-in-law keeps his down and his tail gate looks like sh*t.

Scott

 

Leave the tailgate up. One, it makes almost no difference in terms of gas mileage and two, the cops wont pull you over for having it up.

 

quote from: Ed Fitzgerald, Research Assistant, Dept. of Aero/Mechanical Engineering, U. of Notre Dame

"I'm an aerodynamics engineer. When I was in the U.S. Air Force a few years back, I worked with folks from the Lockheed low-speed wind tunnel. In the 1970s, aircraft production went into a slump, and Lockheed started looking for other customers for its wind-tunnel services. Prime candidates were the auto makers, and Lockheed was successful in convincing Ford, among others, that the wind tunnel would help them reduce drag and wind noise on their vehicles. Needless to say, in the past 15-20 years, Lockheed has learned a lot about car and truck aerodynamics. Anyway, they actually performed drag tests on pickups with the tailgate both up and down, and found that drag was actually LOWER with the tailgate CLOSED! This ran counter to their intuition (and yours). The reason is that a closed tailgate sets up a large "bubble" of stagnant air that slowly circulates around the bed of the truck (we aero types call this a "separated bubble"). When air approaches the truck, it "sees" the bubble as part of the truck. So to the air, the truck looks like it has a nice, flat covering over the bed, and the air doesn't "slam" into the vertical tailgate. If the tailgate is open, or replaced by one of those "air gate" nets, however, that nice, separate bubble in the truck bed does not form (it "bursts"). Then the air approaching the truck "sees" a truck with a flat bed on the back of a tall cab. This is a very nonaerodynamic shape with a very LARGE drag. So, believe it or not, it's best for gas mileage to keep the tailgate CLOSED. Hope this information is helpful."

 

Up or Down?

I was driving across down today, meeting my lady for lunch, on my way I ran into some traffic and decided to take a "detour". Well...long story short I hit a pretty sizable dip and heard a nice thud. I didn't think much of it until I went to close my tail. It was stuck open. It took a few minutes to realize that I had broken the plastic piece that holds the tail pin in. And the tail was virtually hanging on by just the cable on the passenger side. Not too big of a deal, but a pretty dumb thing to fix on a brand new truck! :o

 

if you do decide to drive with the tail gate down 1. put tape on the tabs underneath the loop of booth tail gate straps, those flimsey clips break, just by removing and installing the tail gate....the clip is all that holds the tailgate strap to the inside box, top, beside the tail light.

 

Thanks for all the info. I didn't to well enough in physics to figure that one out. Makes sense now though. And I definitely don't want to screw up my gate even if it did work.

 

I have a friend with an 2002 F-150 and he was bragging about supposed fuel savings with the gate down until a rock came up from his back tire and dented his tail gate. $300 later and his is always up now. It looks impossible for a rock to hit the gate with mud flaps but his did.

 

Well i was driving down the turnpike and got pulled over doing 85 in a 65. The cop walks up to me and i say "whats wrong i have my tail gate up" He said "yes you do"and let me off with a warning.

 

with the tailgate up... last time i went to tracks was throwin down some crapp times but with the tailgate down. i was runnin 15.24 was best time of the night and then last run i put it up just to see if it did make a difference and i ran a 15.48!!! and lost 2 mph with it up... now on long trips if i leave is down i normally get 22 mpg in my truck if i have it up i get about 20... next time im droppin weight so im just going to remove my tailgate and spare tire and prolly rear seat. and see how much of a difference is makes... maybee someday i'll take a tension scale and see how much wind drag i get with the tailbed up... ohh also with the tailgate up.. my speed doesnt wanna go any faster then about 100 but with it down 130 is easy to reach... so may not cause yall any dray but there are many things that play into if u will have wind drag or not with tailgate up or down

 

Then is it true that a bed cover will help with gas Milage ?

 

I seem to remember a study done by a college student that said a soft or hard cover reduced drag by 12%.

other discussions are at

http://www.enjoythedrive.com/content/?id=7021

http://truck-bed-covers.com/Tonneau_..._save_fuel.htm

 

ive always wondered how much i save with a cover on my truck, i only get ten miles per gallon as it is