Potential fuel economy mod?

agreed. myth

air vortex in the bed acts as an invisible pressure wave and net drag remains the
same

drag behind the cab + drag behind the tailgate and body of truck

there is no significant drag caused by the tailgate front-facing surface


on the 2016 tacomas
it is the combination of tonneau cover and the fatter tailgate top which acts as the little whaletail. that fat tailgate top is all about mpg

the 2016 mandated covers for MPG (so many % tacomas must be sold with tonneau covers) really only works if you have some type of random load you are carrying which disrupts the in-bed pressure wave and does increase drag. covering up yo shit cleans it up and sets it back to 'normal drag'

You want to decrease drag on an empty truck you need a full-size cap, with curved tail end and little whaletail

what does increase mpg is how these are designed
or lack thereof

headlight cover design (toyota bubble lights that stick out from the body
we are all used to now and other makers now use)

antenna
spats
mud flaps
chin air dam
mirror design
tail light design
tailgate top design
skid plates
skinny tires
windshield surrounds
side window surrounds
rear bumper

plus every other thing. you want to get the most mpg possible you need
to install extreme bodywork, golfball dimples, and 180psi model-T style tires

 

Interested in your results.

 

When I had my 2011 V6 tacoma access cab 6 speed, I installed a tonneau cover and I consistently got 30 more miles to a tank.

I put the same tonneau cover on my 13 V6 double cab auto, and I didn't notice any improvement in mpgs.

I think it depends on conditions of the truck. Access cab benefitted, but the double cab with the same size bed didn't for some reason.

Toyota and GM puts them on for mpg increase.

 

This was tonight going home, city driving, not a lot of traffic, but catched a few red lights.

 

Not bad... I think this new auto negates the need for a manual. Maybe that's why Toyota only offers the manual on 4wd models... Let's see how reliable it is. Maybe after another 3-5 years, I might consider getting an access cab.

 

The Off Road, which comes without the air dam, has the same MPG as the SR5 with the air dam.
It looks like the air dam doesn't help/affect the MPG at all.

 

That's because EPA isn't requiring Toyota to give different ratings for the OR package.

Just like the 5-lug 2.7L regular cab got the same rating as the Prerunner AC.

 

And this was tonight, in town, driving at 40-45 mph. I'm doing 23-24 MPG most of the time.
No air dam.

 

When I come down from Crawford notch the 7 miles to Atitash I get some thing around 48 MPG. Very short drives will prove nothing.

 

And of course at 40-45 the air dam would not be in play.

 

I understand that. It was just to show that I was doing approximately the same with or without the air dam at those speeds.
I drove 25 highway miles to a cousin's house the other day, at 75-80mph with the air dam on, and I was doing about 22 MPG.
Next time I go there (this time without the air dam), I will keep an eye on the MPG to compare.
Once you pass 60-65mph, it doesn't matter.

 

The coefficient of drag increases with speed the slicker you make something the better it will be at speed. In the case of an air dam it is unlikely it alone will make much difference at highway speeds.

 

This morning, highway miles at about 65 mph.
No air dam.

 

Another 10 miles at 50-55mph.

 

All these short trips don't mean much j102, not clear what you are trying to present?

 

That I don't see a difference after removing the air dam. At least on these 10 or 20 miles trips.

 

You've already shown your bias, that you are hoping that the air dam doesn't help mpg. It's simply not the case and all your attempts to prove that are suspect and not trustworthy.

Other that are reporting a drop in mpg without the dam make sense. That it doesn't have an affect is serious wishful thinking.

 

I don't know why you call it "suspect and not trustworthy", because it doesn't show what you want? I think you are biased too.
I agree it is not nearly a scientific test, all we are doing is our own tests and having fun in the process.
I haven't seen a negative effect after removing the air dam. YMMV.
Go ahead and do your own tests and arrive to your own conclusions, but there is no need to offend anyone.

 

Toyota already arrived at the conclusion that it helps. You are bound and determined to show that it doesn't have an effect when it does.

 

Toyota engineers know better than me. For sure.
Please don't change my words. I said that I haven't seen a negative effect after removing the air dam. The conditions and effects would be different for others. It hasn't made a difference for me. So, I am glad I removed it.