My test isn't scientific, but my Toyota has averaged 17.3 mpg in virtually every tank for the past 2 years. The best I ever ran with my lightest foot was 18 mpg. When I started driving with the tail gate down, it went up to 18.5 and sometimes 19, without trying to be light footed. About 10% better. It seems like its been a fairly consistent increase so now I always drive with the tail gate down. Just doing my part for the environment. [img]/forums/images/icons/laugh.gif[/img]
That's a bummer Rob. Hat's of to you.
Egon
I just got back from a highway trip and got 20.5 MPG with the hard tonneau cover. Before the tonneau was on, I got 19.5 MPG on the highway, so it was a noticeable improvement! I had the same amount of weight in the truck both times.
I'm glad to see I'm not the only one getting in the 20 MPG range. People think I crazy when I tell them I get that kinda of mileage. Made the b-i-l/s-i-l mad the other day when I slammed their new Kia Sorento w/ a small v-6 for only getting about 16 MPG and no more room than my pick-up and not near the capability. The only thing they beat me on was price. I'll stay with my Chevy over the Kia though. [img]/forums/images/icons/smile.gif[/img] Of course I'm impartial also slammed the wife's uncle w/ a 4wd Dodge Dakota also w/ a V6 getting 15.
the best i have gotton with my mazda is 35 with thecover on. but i do have a high flow muffler and intake. makes a huge difference.
Wingnut,
I read of the same study that the airflow in the bed of the
truck creates a bubble which cuts down on drag.
I did a test a few years ago with my tailgate up/down.
I had to drive to GA from NC and back in one day. Five hours
down and five back. I drove down with the tailgate in one
position and changed its position of the drive back.
The bottom line was that the milage was almost the same. It
was off by something like .1 MPG and that was on the drive
down. When I got to GA I had to drive around looking for an
address so I wasted some fuel figuring out where I was
supposed to go. On the trip back I did not have that problem.
[img]/forums/images/icons/grin.gif[/img]
So it was the same truck, different fuel, same weather and
same roads, and the milage was the same.
Later,
Dan McCarty
yap up in deed creates a circular bubble of counter rotating air in truck bed area lowering the amoung of air drafting back and creating a low pressure area thus slowing the truck when the low pressure area isn't there no increase in drag..
so leave it up and in place..
Casual tests (anecdotal, non-scientific) and uninformed surmizes are interesting but mostly useless.
First, this, my kindred spirit: Sorry you let your proff squelch your testing. I wanted to pursue active noise cancellalltion in 1968-9 but acoustics proff laughed me out of his office.
Auto makers do extensive testing these recent decades in attempt to keep the "fleet" average fuel consumption in check. Some of us really got into this a few years back and could find no evidence that any production pickup sold in America got beter mileage with the tailgate down or removed. Ditto for the cargo nets and louvered gates. Previous poster hit the nail right on the head! Aerodynamics of pickup with empty bed, gate up is almost identical to same unit with tonneau cover and measureably better than with gate removed or lowered.
If you believe lowering the gate helps your mileage you probably also believe frogs cause warts, or kissing a frog might turn it into a prince(ss) or any other number of things often accepted on faith but never scientifically measured. How about moth balls added to the gas tank for extra horsepower? Keep your razor blades in a small pyramid to keep them extra sharp for a long time. Junk science abounds! Remember all those TV advertisements last year for electrical muscle stimulators. Where did they go? Visit any auto parts store and for a good laugh look at the plethora of chemicals availlable to cure everything automotive. Some of the stuff may work some of the time in some cases but generally it is "snake oil", right up there with getting the x-rays "touched up" because you don't want to have the operation. What about putting aluminum foil in your hubcaps to foil police radar.
Pat
"I'm not from your planet, monkey boy!"
Pat, two things you've said got my attention.
<font color="blue"> "Auto makers do extensive testing these recent decades in attempt to keep the "fleet" average fuel consumption in check." </font color>
In the 70s, Congress mandated autos have a fleet averge of 27.5 mpg. They also mandated a fleet average of 20.5 mpg for light duty trucks (minivans, pickups, and SUVs). Legislation proposed this year is supposed to mandate improved mileage in light duty trucks. A 20.5 mpg average! We know its not met by the pickups, but those with the sloped nosed minivans know how the average has been brought up.
As for the auto makers, they gave us the Vega, the Pinto, among others, and this year have publicly advertised the quality of their vehicles in the past was lacking. They said this admission was doen to try and regain trust. Simply put, the major auto makers have about the same credibility as junk science. Believing them takes real faith.
You also said, <font color="blue"> If you believe lowering the gate helps your mileage you probably also believe frogs cause warts, or kissing a frog might turn it into a prince(ss) ... </font color>
It seems to me that when you drop a tailgate, you change the shape of your vehicle--and change it's aerodynamics. Some believe that aerodynamics affect mileage. At least in my thinking, it takes more faith to believe that dropping the tailgate has no effect. I can't say dropping the tailgate cause warts on a Chevy, or turns a F-150 in a prince, but to think it has no effect on mileage
Pat, I can agree with you whole hearted on one thing,
<font color="blue"> "A mediocre day in the country beats a GREAT day in the city!" </font color>
-Jonathan
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