For the past few weeks, I've been moving things into my new place from mom and dad's. Because of this, I've just left my tonno cover rolled up (laziness is the cause of this experiment). I've recorded my mileage with the cover on and off, durring the last few weeks and figured I'd post my findings for anybody interested. The truck is a 2004 Edge, 4.0 liter, 5 speed with 4.10 gears and 33 inch tires. The tonno cover is a soft, snap cover made by TruckTek The results are skewed a bit because of the larger tires, and transporting some light loads.
For normal driving, mostly highway but with a lot of traffic lights in between, and little city driving, my mileage with the tonno cover on averaged out to be 16.67 mpg. With the tonno cover off my mileage has averaged 16.50 mpg. Once again, the true numbers are skewed due to the larger tires.
I used a number of $2.80 for the price per gallon of gas and divided that by my mileage. This gave me $0.168 as the cost to drive one mile with the tonno on, and $0.170 as the cost to drive one mile with the tonno off. Next I used a number of $200 for a toono cover, I believe that's about average. If my calculations are correct, it would take 100,000 miles of driving with the tonno cover on to make up the savings to pay for the expense of the tonno cover. I made this up pretty quick, so it is possible that I have made some mistakes, if you catch any, feel free to post.

CLIFF NOTES VERSION:

The tonno cover will save you roughly $0.002 per mile. You'd have to drive 100,000 miles with the cover on in order to make up the price of a $200.00 cover.

 

Lol thats funny...I'd rather put 200 in my tank hah. Good info anyways

 

yes but you need to weigh the advantages and disadvantages of having a tonneu cover.

to me i dont care if it gets worse with one, i want one.

 

Doesn't get worse, it gets better, but very little for the money. It is nice to have, keeps my tools and whatever else back there hidden.

 

i like having more space to store stuff in the bed without worrying about theft...

 

Yeah, mine isn't "much" better with the tonneau, but I love mine. It retracts, and still is a hard top.

 

I do too much tailgating to have a tonneau. I always have my bed filled with people.

 

Pretty good, John. Way back in GenEdge days, some of us did some testing and concluded that the Ranger does not have a "bed turbulence" problem for some reason of the aerodynamics -- though none of us could point to why.

But quite a few people with tonneaus tried this and nobody got any data supporting that idea that a tonneau saves any money. All the results showed either a slight gain or slight loss -- but overall it was a wash.

I don't doubt that some pickups have a problem with this -- just not the modern Rangers.

 

I have also done this a while ago just after i put the 32's on i can avarage anywhere from no difference at all with it to about 2mpg. its all in driving habits...

 

I bought my 2004 4.0 Ranger Edge in May 2004. I have tracked the fuel mileage of my truck for every tank of gas that has gone in. That means that every time I went to the gas station I filled the truck all the way up, then recorded mileage from the trip meter and figured out what my fuel economy was for that tank. This is all recorded in an excel sheet. I now have 30895 miles on the truck, have filled up 133 times and purchased 1718.91 gallons for a total of $3684.40 (ouch). Total average fuel economy for the truck is 17.97 mpg.

The truck was bone stock for 13548 miles. During that time my average fuel economy was 17.74 mpg.

At 13548 miles I installed a K&N air filter. I didn't expect any gains in fuel economy, but I noted the change just to see. Without making any other changes I drove the truck for 14452 miles. During that time my average was 17.94 mpg, basically no change.

I then installed a tonneau cover at 28000 miles. Since then I have driven 2895 miles. My average has gone up to 19.18 mpg, however, this data is not as good of an average as the other data because I just don't have as many data points.

Bottom line: I haven't noticed much change since I installed the cover. Its nice to have a place to keep things hidden and dry though.

Oh Yeah, for all the tailgate droppers or tailgate removers: There was no noticeable difference up, down, or off.

 

The numbers are too gray area to call it anything but a wash. Sooo many factors, that unless the numbers come back blatantly higher or lower with the cover you can't really determine either way as to its benefit. I say, Tonneaus are for covering your bed, not getting better fuel mileage...

 

i noitced a difference of about 4mpg more on my 92 with the tonneau and no difference on my 02 its the same tonneau cover too

 

Must have to do with the cab design then, Just the way the air circulates off the end of the cab and into the bed?

 

good i need to save gas money anywho

 

Yes, that's why I said the more modern Rangers. The older squarer ones must have different aerodynamics which influence all this.

 

I read somewhere that leaving the tailgate down rather than up (without a tonneau cover) is actually better. It gives more downforce and somehow creates LESS drag, this was in an auto magazine somewhere during the summer. They didn't do any tests with a tonneau but said that it would help if anything for mileage. I have one and can't tell if there's a gain or not. I like how it looks and for putting stuff under it though.

 

Yah but there is a downside to no tailgate. I don't remember who explained this or who told me(god everything I know could be smart, if I just had sources! I'll jus say John Griggs told me). But if you don't have a tailgate on your truckbed then the bedside support is gone. so like, your bed can either bow in our out over the years. Also in a carcrash, your chances of F'ing up your bed are greater since there's that crosssupport we call teh tailgate.


But, hey, tailgate down looks cool!

Aaron

 

I keep a fuel log for my truck. I've logged every gallon of gas I've pumped through this thing since I took delivery from my dealer back in '03. I've done entire tanks w/ and w/o the tonneau installed, closed, on summer vs winter (tight vs loose) snap setting and I've yet to see any conclusive differences either.

The tonneau may save you some fuel, but not enough to be worthwhile.
I couldn't agree more!

As for the tailgate up vs down, this has been discussed at length. Somewhere around here there is a discussion about a paper done by some Mech-E college students where they wind-tunnel tested a model of a pickup body w/ different types of 'aerodynamics enhancements'. The moral was that pretty much none of them helped much.. except dropping the tailgate HURT aerodynamics quite a bit! It destroy's a relatively high pressure bubble that forms in the bed and creates quite a bit of drag behind the cab..