Many of us have driven or own pick-up trucks, so here is the question: Do you reduce drag and save gas to have the tailgate of an open bed truck up or down/removed?

Did anybody see the mythbusters episode where they tested this? It was pretty neat.

You get better mileage when the tailgate is up, it creates a air bubble in the box that helps the air flow over the top of the box.

Actually, did the mythbusters say that tailgate off with a cargo net was the best mileage?

I'm with Phil,been a while since I seen it but think there was slight increase with cargo net. Other wise tailgate up.

I will have to look up that episode tonight on Netflix and watch it again. I was fairly certain that the tailgate up was the best. If I remember correctly, they both guessed gate down, as did I, and gate up won. I could be completely wrong... LOL memory is not my strong suit.

Better gas mileage or not, I always hated having the tailgate banging around every time I hit a bump when I had it down.

They also tested whether or not you should tailgate a 18 wheeler for better gas mileage. They said they wouldn't recommend it...but it did work

I would never had thought that to be true.
Seems like it creates drag, but the air bubble makes sense.
I'll have to test that theory on the way to IG see if there's a difference in gas mileage.

Yup, tailgate up was the winner in that episode.

The thing on the back of the space shuttle was what got me thinking about it.

That Myth Busters was the episode I saw which was counter intuitive. I forgot the name of the show, but remembered that they actually showed it via a smoke/wind tunnel test. The smoke created a rolling ball in the bed of the truck with the tailgate up, and the air stream skimmed right on top of it. I think it was the difference between the airstream hitting and pushing down the bed of the truck, with the tailgate down, and not touching the bed at all.

I still see a lot of trucks with the tailgate off, down or replaced by a net.

I am guessing a cap the same height of the cab would be the most effective airstream-wise but the additional weight might offset the gas saving difference between that and no cap, tailgate up.

BTW the tractor trailer thing, anyone who rides long distance cycling knows that if you draft behind someone else, you expend less energy. It's suprising how much easier it is to ride right behind someone. That's why you see them riding that way in races.

I usually had a cap on any of my 5 pick-ups that I had over the years 90% of the time....otherwise the tailgate would be closed (up).

Put side boxes and behind cab tool box on style side pickup and you shoot you self in the foot,as far as highway mileage is concerned because they are higher than tailgate. Same as running with tailgate down.

That's Called Drafting.

Bob,

Interesting blog, but with just one sampling, not scientifically viable. First to be statistically viable, the test has to have a large sampling (not one guy in a truck). They each have to go hundreds of miles, plus all the extraneaus factors have to be removed. For example anyone who pilots an aircraft know that difference in temperature, humidity, wind direction and speed makes for different air densities and affects drag. Did the pickup guy measure these (not only daily but hourly) to create a formula for taking the differences on different days into account?

On the ground there could be different traffic patterns. One day more traffic than the other, or they stop at more lights, or the same factors that affect air density, could affect the tires grip on the road, etc. Was he carrying more in the truck one day than the other. How big a lunch did he eat each day and how much beer did he drink.

Granted the Mythbusters only used one example, though I think they used a track, but when the engineer in the wind tunnel talked about the effects of drag, the consenses was that the tailgate down actually created more drag in the slipstream.

They have used wind tunnel with smoke indicators thousands of times at different labs around the world to look at drag with vehicle design, athelete performance, cyclist positions, even the drag of different swimsuit materials, etc. The more drag, the more energy needed to move...

So theroretically you get better gas mileage with the tailgate up. The question is however, how significant is that savings? A few pennies an hour, a day, a week, a month? Someone someday will either come up with an answer using drag coeficients of wind tunnel patterns, or will drive a whole bunch of identical trucks at an indoor track for thousands of miles.

Nicole, who really enjoys all the links Bob provides the forum and hopes Bob still likes her after this post!