Does a tonneau cover help with gas mileage?

Always thought it did?

 

How? I doubt it does.

 

Nah not enough to make a huge difference. Most of the air is going over the bed due to airflow from your hood and windshield. The only time you'll see air hitting your bed is when you are going downhill.

When they test these trucks to get real world MPG it's without bed covers

 

It depends on how many places you go to the right of the decimal point when calculating fuel mileage.

Nothing new here. When gas prices doubled in the 1970's going from $.45/gallon to over $1/gallon almost overnight everybody was looking for ways to get better fuel mileage. This was when trucks got single digit fuel mileage. My 1975 Jeep truck got 6 mpg city/11 mpg hwy. Yea, $1/gallon sounds cheap, but with that fuel mileage and people today making more today/month than most made in a year gas was much more expensive than today at $3/gallon.

Every truck and 4X4 magazine in the day conducted tests on every imaginable modification to trucks including caps, tonneau covers, tailgates up, down, and off. The results were mixed. In some cases fuel mileage did improve, in some it got worse, and in others it made no difference. But it was never more than a small fraction of 1 mpg.

Since then the tests have been replicated multiple times including at least 3 times on Mythbusters. The 2nd best way to get better fuel mileage is to drive conservatively and keep the truck well maintained. The best way is to drive something that gets 35 mpg+ until you need the truck.

 

Yes, you have less money to put in the tank

 

Nothing significant. If you want better gas mileage, about the only thing that will have a significant value would be a cover that started at the top of the cab, and sloped down to the tailgate.

Would look uglier than sin, but would help the air keep laminer flow across the bed. Vortex generators would help as well, to keep the air attached in laminer flow.

Now, just need to find a mfg to make it... Wait...

 

put a big wing on the tailgate it helps with down force and makes the truck go faster

I dont think it would matter tbh, if youre having mpg issues its a truck it is what it is

 

Turbulent air is terrible for fuel economy. The only way to make it better it to get the air to follow the body, in a laminer fashion. Any right angle (think back of cab) is going to cause massive turbulence, and cause terrible gas mileage.

 

No.

 

Negligible.

 

Ran it for a year and saw no deference.

 

I think Myth Busters or similar did an experiment on it. They found no difference. They chalked it up to aiflow up and over the cab and enough stagnant air pressure to keep most of the wind out of the bed. Something like that

 

I notice no difference. If it does, it’s so minimal it doesn’t even matter. Maybe you will save 25-50 cents per tank of gas.

 

No it does not.

 

I ordered my cover right after I bought the truck. Took about 3 weeks to come in so I only had a couple of tanks to compare, but there was no real difference.

 

Wheres myth busters when you need them?

 

Probably, yes only at speeds faster than the truck is capable.

 

Might save you a few bucks in gas money over the life of the vehicle, but otherwise not really! But they do keep stuff in the bed (relatively) secure and dry which is their primary function.

 

A cap might help. The square back is good for mileage; station wagons can be better than the sedan equivalent, however, modern wagons with more rounded ends may not be as favorable. Alfa Romeo changed their 1960s SZ race car with a round tail to the TZ with a square tail after wind tunnel tests showed that resulted in better aerodynamics. This is not an intuitive result....

 

Absolutely. Anyone who knows anything about aerodynamics will tell you that the bed area uncovered, with the tailgate up, is horrendous to the aerodynamics. Just lowering or opening the tailgate is a help, but even that is not as good as either a tonneau cover or a shell. Now, obviously this is not a big deal for around town driving, but on long trips on the interstate, it DOES make a difference and I can attest to it. When I had my old 96 Xtracab, I was going to do a cross country from the San Francisco Bay area to FL, NC, and then back across to the west coast again. I needed a tonneau cover because I was going to be carrying a bunch of stuff that I wanted somewhat protected from the elements, but I didn't want to spend a lot of money because with the exception of this trip, I didn't want a cover on the truck. So at that time, I found a nice one online from someplace in AZ, for $175 [this was 2005], no tax and free shipping. It installed easily and I went on my trip. Almost right away, I could see that I was getting better gas mileage, but I just thought I was seeing things or something. But with every fill up, and this is calculating via good old mathematics, as the truck had no electronics on it back then, I constantly got between 28-30MPG, which I never got on local freeways on short trips without a tonneau cover. So by the time I made the whole trip, I figured it out and my dollar savings in gas alone, actually ended up PAYING for the tonneau cover! I only used the tonneau cover one other time, and when I sold the truck in 2019, as part of a great deal I swung, I included the cover with the truck when I sold it. The bottom line is that on basic around town or short interstate trips, you are not going to notice any difference, but on long trips like my cross country trip, the improved gas mileage is very much noticeable...