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These trucks have pretty terrible aerodynamics, but with the gate up the mismatch between the cab and bed creates a vortex of circulating air that cushons the air blasting over top of the cab and helps it ride off the back in a smooth fashion. With the tailgate down that vortex collapses and airflow over the cab doesn't flow off the back and that actually hurts gas milage.
Look at the Nascar truck series, the rear spoiler on those things is almost the size of a tailgate, that is no coincidence.
First I'll say I read the first 2 responses. Years ago there was a magazine call Pickup Van and 4 wheel drive, anyone remember that one? They did a test and their results were that you got 6% better gas mileage with the tailgate down. I assume down would be with the tailgate flat with the bed. If you let the tailgate clear down you would create another wind damn.under the truck. My reasoning would be you would get better gas mileage with the tailgate flat with the bed, creating no air damn. I think tests can be deceiving, not meaning to argue with anyone.
I've heard fuel economy is worse with tailgate down, too. I dunno. Maybe it depends on the year? Trucks sure have changed body styles a lot over the years. My slick has the aerodynamics of a barn door. One thing though, I can roll a window completely down at highway speeds and when the wind is just right it's dead calm enough in the cabin to light a match. In my Ranger though, rolling a window down at speed is like entering a tornado.
Fuel economy on these rigs is mostly a losing battle, but does anyone else recall that orange bullnose F-250 diesel that some guy claimed getting 20-30 or some mpg? he put a lot things on it like plexiglass over the headlight buckets to smooth out the front and eliminate wind drag. Lots of skirts and air dams too. There are pics on the net.
I have a friend that swears he gets better mileage with the tailgate down, but I saw the same Mythbusters that Conanski referenced above, so I don't know.
It'd be pretty easy to try. Fill up and drive everywhere with your tailgate up and figure your mpg. Then fill up and drive everywhere with your tailgate down and figure your mpg. To get a true test you'll probably want to do this two or three times to compensate for different driving locations and conditions.
Personally, I've seen too many people ruin their tailgates by forgetting it was down and backing into something to make me want to try it.
If you drive with the tailgate down over time the top 6 to 8 inches of the tailgate will be very chipped up or it will look like it was sandblasted espesially if you drive on gravel roads.
Depends...
I think it depends on your average speed over time.
Driving in the city, under 40, I see the tailgate up as a brake, causing you to use more fuel.
Driving on the highway, over 50, with the tail gate up, as I recall, myth busters said the air circulating like a rolling tire in your box, will actually 'LIFT' the box, making the truck lighter on the hwy, hence using less fuel.
So, I've always wondered about tonneau covers?
Do tonneau covers give you worse fuel mileage?, more weight, and does not create the air circulating in box.
These trucks have pretty terrible aerodynamics, but with the gate up the mismatch between the cab and bed creates a vortex of circulating air that cushons the air blasting over top of the cab and helps it ride off the back in a smooth fashion. With the tailgate down that vortex collapses and airflow over the cab doesn't flow off the back and that actually hurts gas milage.
Look at the Nascar truck series, the rear spoiler on those things is almost the size of a tailgate, that is no coincidence.
Yes, believe it or not that is absolutely correct.
A good friend of mine is an aeronautical engineer, and I mentioned this to him years ago, just wondering out loud. This is what he told me.
When he was in university, it was a class aero dynamics project. Which is better? Up or down. They actually did all the engineering for this and determined that there is a boundary layer created in the box on the top with the tail gate up. It creates a laminar air flow over the box and over the tailgate. With it down, it creates some type of drag inducing vortex.
Ive also been told by aeronautical engineers, it doesn’t matter as much to what you do to the front of an aerodynamic ‘whatever’ - it is the aft/tail area that creates the most drag.
Yes a tailgate in the upright position hinders mileage..Thats why they make Toneau covers.....It's also true that driving with both windows down kills mileage unless you have a rear center opening window or open the vent windows a tad to deflect the wind................
I gained 2 mpg with my one n only tailgate mod but the worst is when the tailgate was acting like a parachute tuck-lifting the rear when decellerating over worrying about mileage gains except for the fact that I get more drive time out of the same tankful so how can't that be notable?.......I drive my 2wd over 95mph alot as it handles like a NasTruck ...
Nevermind the fact that its 29 years old as it drives like its quite young on the inside and even better than Ford built it with modifications done to the twin I-beam frontend that I don't think anyone else in the world let-alone anyone on this forum has but me...........
Its funny when I pass other fellow Ford guys on the highway and some are death gripping the steeringwheel..Especially in the newer F250's and Im cruising by one finger on mine..............LOL
These modifications were done over 13 years ago....My alignment guy loves aligning my ride......Its very easy to get it set arrow straight on all 4 wheels................
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Slideshow: Called the Fortress, the 850-horsepower pickup combines Raptor underpinnings with military-inspired features, survival equipment, and a starting price of $285,000.
