Tonneau Cover Range Improvement numbers

[GDN]

My theory is if a tonneau cover made that big a difference Ford would be installing them on every truck. I would think they could claim it improves their CAFE numbers - or whatever numbers they try to hit. In the massive numbers they buy/sell they'd get them for $$200 each and add $800 to the price of the truck. Why would they pass u that mileage for the govt and that kind of profit?

I like to push conversations to the edge and will say that if you are worried about the amount of electric/gas savings from a tonneau cover and everything you need to carry can fit under it, you probably need to look at the bigger picture and dump the truck. Get you a smaller sedan and load it up, you'll still get better efficiency and now you're really saving. Bottom line to that however is that we aren't really all that concerned about saving electricity or gas, we just want to say we are doing the best we can to save a penny when we are driving the pound foolish thing down the road.

Don't get me wrong though, I don't care about the mileage as long as I have enough chargers along the route and I'm not giving my truck up either.

Sponsored

 

[Cbowe]

I can obsess about this stuff... but obviously if I were really concerned about vehicular efficiency, I'd be driving a Prius instead of a Lightning.

So, the theory is this: a tonneau cover lowers the Cd (coefficient of drag) of a pickup truck. That is almost universally true, for reasons that are probably intuitively obvious. The tailgate is an obvious apparent wind catcher. Try to carry a sheet plywood with the flat side facing the wind on a gusty day, and you will appreciate aerodynamic drag.

I've linked a study by SEMA that squares with my understanding of aerodynamics, and especially vehicular aerodynamics.
https://www.agricover.com/downloads/pdf/2007_windtunnel.pdf

Aerodynamic drag becomes increasingly dominant with increases in speed (going up at the square of speed, unlike rolling friction, which stays nearly constant). Power required, therefore, goes up with the cube of speed, (because you are both going faster and pushing harder). Power times time = energy usage. Range increases by the same factor as claimed fuel mileage increases.

If you do a lot of highway driving, (and charge at the robber barons' fast chargers) then a tonneau cover can justify its cost even if you have no other use for it. The range reduction you might imagine from the increase in weight is not measurable, because even the rigid covers are so light. (Do you stick your nose out the window and aim your sneezes backwards to give the truck a little boost?).

My range seemed to improve by about 10 miles (about 5%) after installing my ($100) fold up tonneau cover. However, I was driving fast on the day that I checked, and I don't bother to check on slow driving days, because I know there is no measurable difference. So read the article if you are so inclined, and figure in your style of driving. No "average" gain in range will likely apply to your use case... and my presumed gain won't apply either, unless you happen to drive exactly like me... on the same roads... at the same temperature... in the same wind conditions.

AC and heat have a significant effect on range, as does terrain and many other things. (That is why I used the word "seemed" above -- a definitive, reliable, repeatable test is quite difficult, if not darn near impossible.)

Related: My front air dam extension (the retractable part that extends at 40 to reduce aero drag) fell off a while ago, and I have not been able to detect any difference in range. I tend to drive at close to the speed limit. Maybe if I drove at 20 over all the time, I'd notice a difference.

I did a video on this did it on an off and it made no difference

 

[2sleep]

Have not read all of the posts so someone may have mentioned this before. These covers are not weightless. Neither is the stuff that I carry around in the frunk or cab that I rarely if ever use. Things like the 110/220 charge kit, trailer hitch, air mattress setup for the back seat, rear floor coverings, etc. If you are really obsessing over your mileage, go for the low hanging fruit first. Keep your speed at 55 MPH, don't run your heater or A/C or your stereo, dim your interior lights and put your big screen to sleep.
Or just enjoy your truck!

 

[Cbowe]

Have not read all of the posts so someone may have mentioned this before. These covers are not weightless. Neither is the stuff that I carry around in the frunk or cab that I rarely if ever use. Things like the 110/220 charge kit, trailer hitch, air mattress setup for the back seat, rear floor coverings, etc. If you are really obsessing over your mileage, go for the low hanging fruit first. Keep your speed at 55 MPH, don't run your heater or A/C or your stereo, dim your interior lights and put your big screen to sleep.
Or just enjoy your truck!

Weight has almost no impact on range as shown by the video that Aging Wheels did

 

[PJnc284]

I wouldn't quite say no impact on range. Really depends on speed. More stop and go and that weight will certainly matter. At interstate speeds, aero is the killer.

 

[2sleep]

So I could load the bed with sand and have virtually no effect on range!

 

[Cbowe]

So I could load the bed with sand and have virtually no effect on range!

If you stuck to the weight limits of the truck correct it would have very little impact as compared to aero for towing as an example or in this case the substantially less weight that is being talked about here with a bed cover. It would basically be within a statistical margin of error

 

[2sleep]

Agreed that you can't really make a brick aerodynamic. But IMHO, what ever small loss or gain you would have having a "closed" bed verses an open one is less important than the terrain and/or headwind/tailwind and speed.

 

[Cbowe]

Agreed that you can't really make a brick aerodynamic. But IMHO, what ever small loss or gain you would have having a "closed" bed verses an open one is less important than the terrain and/or headwind/tailwind and speed.

Pretty much and the open bed ends up filling with an air bubble that allows the air to flow right over it so it ends up not really making a difference cover or not

 

[Pitbull2o08]

I assume you are just being belligerent for fun, but in fact, there is nothing in the paragraph you quoted that is false. And oddly, you go on to agree with my several points. Wierd.

The First Statement:
"So, the theory is this: a tonneau cover lowers the Cd (coefficient of drag) of a pickup truck."
That is entirely true and very well known by every aero guy or gal at all the manufacturers. Does the theory pan out in practice? That's another question. But the answer there is also well known, and Brad Richards of Ford (see the autoblog video) puts its well: "Tonneaeu covers are more efficient." He goes on to say that the tailgate top surface mimics the last 6 inches of a tonneau cover.
So the first statement 100% true. Anyone arguing otherwise, would have to know essentially nothing about the last 50 years of auto aerodynamics studies.

The Second Statement:
"That is almost universally true, for reasons that are probably intuitively obvious. " It is 100% true that the theory is universally recognized, by those with subject matter expertise. Granted, there are loads of people who know nothing about aerodymanics, but I think, in context, we can say that I am not treating their theories (whatever they may be) as a "theory". They are instead "hunches". For example, the hunch that lowering the tailgate would reduce drag is clearly not useful. The SEMA tests. long ago showed that not to be valid, as had tests elsewhere at manufacturer's wind tunnels decades ago.
So, again: 100% true.

The Third Statement:
"The tailgate is an obvious apparent wind catcher." No one but a fool would disagree with this, and even you agree: "The tailgate does trap air," you say.
100%, unambiguously, and simply true.
(The second part of your statement is not strictly true without further explanation, given that local velocities within the general bed bubble are actually substantially higher that the free stream velocity, and therefore of lower pressure. Bed blowing would help with your theory.

The fourth statement:
Try to carry a sheet plywood with the flat side facing the wind on a gusty day, and you will appreciate aerodynamic drag."
Even people with essentially no aerodynamic training or exposure to physics would agree with this statement, unless they have led very sheltered lives. I might have gone on to say "Hold the sheet at its trailing edge, and with an angle of attack of 10 degrees, and as it flips over on top of you, you may also gain an intuitive understanding of lift... and even aerodynamic center and moments" .
100% true and known to anyone who has given these issues any thought.

So, were you hallucinating, or perhaps responding to someone else's post?

Are you thinking the Brad Richards is a fraud? What do you think his motives for lying would be?

I can’t explain fluid dynamics to you if you’re not capable of receiving the information. Good day.

 

[WXman]

Didn't Mythbusters test a truck with and without a tonneau cover using instrumentation? They found that the cover did not help.

I have driven my Lightning on the same daily commute for the last several months. When I installed the hard cover on it I saw ZERO increase in mi/kWh. Not even a tenth.

 

[ZeusDriver]

I can’t explain fluid dynamics to you if you’re not capable of receiving the information. Good day.

Nevertheless, gosh golly I sure appreciate your trying to do so. I suffer from IIS (idiopathic idiocy syndrome) so struggle to grasp anything more complicated than making toast. Is there a lynch party being organized to hang Brad Richards, who is on record as the Ford representative who claimed (fictitiously, apparently) that tonneau covers improve aerodynamics, as proven in their full scale wind tunnel? Let me know who, precisely, did the DOE and SEMA studies that showed the same effect, and I will gather up some of my idiot friends to lynch the perps.

 

[02Reaper]

Nevertheless, gosh golly I sure appreciate your trying to do so. I suffer from IIS (idiopathic idiocy syndrome) so struggle to grasp anything more complicated than making toast. Is there a lynch party being organized to hang Brad Richards, who is on record as the Ford representative who claimed (fictitiously, apparently) that tonneau covers improve aerodynamics, as proven in their full scale wind tunnel? Let me know who, precisely, did the DOE and SEMA studies that showed the same effect, and I will gather up some of my idiot friends to lynch the perps.

I think the point that can be made here in this thread is that while something may show up as helping in a wind tunnel, that doesn't mean it will make a seeable difference out on the road. The wind tunnel is a controlled environment with wind flowing in a controlled way. Out of the wind tunnel, the wind is no where near controlled.

 

[ZeusDriver]

I think the point that can be made here in this thread is that while something may show up as helping in a wind tunnel, that doesn't mean it will make a seeable difference out on the road. The wind tunnel is a controlled environment with wind flowing in a controlled way. Out of the wind tunnel, the wind is no where near controlled.

Absolutely.

 

[jimfigler]

Nevertheless, gosh golly I sure appreciate your trying to do so. I suffer from IIS (idiopathic idiocy syndrome) so struggle to grasp anything more complicated than making toast. Is there a lynch party being organized to hang Brad Richards, who is on record as the Ford representative who claimed (fictitiously, apparently) that tonneau covers improve aerodynamics, as proven in their full scale wind tunnel? Let me know who, precisely, did the DOE and SEMA studies that showed the same effect, and I will gather up some of my idiot friends to lynch the perps.

I just took my hard cover off last week to move a treadmill. I was lazy on putting it back on immediately. Guess what, my efficiency was the same as it always was. No perceivably drop and no perceivable gain when I put it back on.

Sponsored