Anyone notice a difference in gas mileage after installing a shell, good or bad? I'm getting ready to purchase a snugtop super sport (cab high) and curious if it will affect mileage.
I had a Leer on my 02 Tundra 4X2 for 6 months. I didn't notice any change in mileage that was clearly due to the shell. There probably was but the other factors that affect mileage, temperature, driving speed, towing the boat,etc all figure in and it would take condiderable calculation to figure out. I do know that the biggest negative effect on mileage is speed. Once I start cruising at over 70 to 75mph the mileage drops off big time.
There are people who will argue this until they are blue in the face, but the fact is, no box cover will improve gas mileage!
That includes soft covers, hard lids, and full toppers. Years back GM & Ford both did wind tunnel testing to see how much of an improvement leaving the tailgate down or using one of those "air gates" actually had on the vehicle.
They both concluded that neither helped in gas mileage as the air actually passed over the top of the cab and over the tailgate, not actually get caught by the box.
I know, almost every manufacturer of these covers and shell CLAIM that they do, but how many of those have this very expensive wind tunnel testing equipment?
I have a soft cover myself but by all means did not buy it for improved gas mileage, but rather to protect things and conceal them from the prying eye.
If you wasted your money on a cover only to think that you will get it back by saving on MPG, you made a mistake.
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1996 T100, 180,000 and counting
I've put a Snugtop supersport shell on my Tundra about 1 month after I got the truck (last January). I don't believe it hurts the mileage one bit, the shells are pretty darn light. The last truck I had was a Toyota extracab 4x4 with a Leer shell that was flush to the cab for the first couple feet, then angled up about 1 foot above the cab. It also didn't adversely affect the mileage, at least, not any measureable amount.
The best mileage I've had with the Tundra with the Snugtop (and I've repeated this two other occassions on the same route) was from Paso Robles to Redondo Beach (Hwy 46 to I5, to the 405). Averaged 70mph and the mileage was an incredible 19.1 mpg. In town I average between 12 and 14 mpg if I keep my foot out of it (and GEEZ that's hard to do.........).
This surprises me a little. I can understand that the soft covers or hard lids don't improve aerodynamics, but a full shell? Seems to me the shells would provide the same sort of benefits the old long-body 917 Porsches pioneered. The "quotes" in your link makes sense for lids, but they don't really address full shells. Are you sure this applies to shells (I assume this is what you meant by "full topper").
That includes soft covers, hard lids, and full toppers. Years back GM & Ford both did wind tunnel testing to see how much of an improvement leaving the tailgate down or using one of those "air gates" actually had on the vehicle.
They both concluded that neither helped in gas mileage as the air actually passed over the top of the cab and over the tailgate, not actually get caught by the box.
dpeete, I agree with you (to an extent). My guess is that the shell DOES has a positive influence on the aerodynamics of the truck, but not to any extent items such as canards or winglets do on airplanes for THEIR gas mileage or manuverability. The small aerodynamic improvement from adding a flush or slightly above cab shell may get you a couple miles farther on a full tank of gas, but the effect to mileage so slight that it's not real noticeable (on the highway at a steady speed). I think it may have some positive effect at a specific speed and under specific conditions (as I've found so far just on one particular stretch of highway..and I don't understand it all yet, either, to tell you the truth...all my other highway driving has been from 17-18 mpg on the average). But remember, we're dealing with a whole bunch of friction and weight that is impossible to take out of the equation, and very hard to counter when the thing you're trying to counter it with also adds more weight to the truck. Take a look at cars that do get good mileage, or cars that are built to get good mileage, like those hybrids. They have things like lightweight fender/wheel covers, skinny tires and pitched windshields to assist their aerodynamics and mileage.
That said, the opposite is true for street driving. There, the aerodynamics don't come into play as they do on the fwy. In the city, you're dealing more with the adverse effects of weight and friction. That's why I think I get WORSE mileage in town, due to the extra weight of the shell.
Anywho, from my experiences, that's my take on it.........Bottom line, get the shell if you need it for another reason than improved gas mileage, because it'll never end up paying for itself if you do any city driving with it on.
Bbbutch.......just want to let you know that there's no rule that I know of that says you have to get Shell gas if you have a shell on your truck (lol.......sorry, I couldn't resist........).
I haven't noticed a difference in gas milage - not sure if the aerodynamics and weight cancel each other out, or if a reduction in gas milage is just not noticable. But the added weight and bulk of the shell have made me drive a little differently - feels like a much larger vehicle, and I take her a bit easier now.
Originally posted by peid That includes soft covers, hard lids, and full toppers. Years back GM & Ford both did wind tunnel testing to see how much of an improvement leaving the tailgate down or using one of those "air gates" actually had on the vehicle.
They both concluded that neither helped in gas mileage as the air actually passed over the top of the cab and over the tailgate, not actually get caught by the box.[/i]
Have you ever ridden in the bed of a pickup at highway speeds? If so, did you notice the wind blowing directly on you if you were sitting near the tailgate? We hated sitting next to the cab, the wind caught by the tailgate caused dirt to blow back towards the cab and get in our eyes.
I still believe the open bed with tailgate up creates drag.
__________________ White 2000 Limited Access Cab, V8, 4WD, TRD with 223,040 miles
MODS: SUSPENSION: front - Cornfed 2" lift, rear - TRD add-a-leafs. INTERIOR: Sony MEX-1GP CD Receiver, tinted windows. EXTERIOR: Ventvisors, Covermaster Tonneau Cover, UTR bed liner, Reese hitch ELECTRICAL: Alarm and remote start package, Prodigy Brake Controller ENGINE/DRIVETRAIN:BF Goodrich AT KO LT285/75/R16 wrapped around Mickey Thompson Classics with 3 5/8" backspacing in front of brake calipers and drums painted red. Cat Back dual custom exhaust with glass packs and 2 1/2" Stainless tips straight back. Air intake box mod.
I've had an A.R.E. LS2 for almost a year and can tell a slight increase in hwy mileage. The best I've gotten is 21 mpg. I average 19s, but drive 70 mostly hwy miles a day. I can tell a definate improvement in handling because of the tonneau. The wind doesn't blow the truck around as much.
I had a 1500 Dodge Ram 5.9l V8. Used a soft tonneau and got reasonable highway fuel economy. I put a Snugtop Top Gun shell on it and my fuel economy went down, averaging 75 MPH on the highway and could feel the extra drag in throttle response (or lack thereof). I currently drive a Tundra 4x4 V8. When I put a Snugtop hard tonneau on it I immediately noticed reduced drag on the highway at 75 MPH and slightly increased throttle response. Fuel economy increased about a mile to the gallon, maybe slightly better. I bought it for the security but increased fuel economy was pleasing. No change in city driving fuel economy though. I've driven the truck with the tailgate up/down on the highway with no perceivable difference, although fuel economy was not measured.
The main source of drag is the air collapsing abruptly behind the cab. A tonneau helps taper the air down and reduces the turbulence (ie drag). A cab-high shell does neither and still allows the air to have to collapse dramatically behind the truck and creates similar drag to an uncapped truck. This is why bullet manufactures use a boat-tail design as opposed to a flat base - it allows air to come back to itself with creating so much turbulence and results in far better ballistics.
sigmundsauer, that was a well written 1st post and good analogy (to the boatail of a bullet.......ah, hand loading.......another one of my little vices). I also agree with your assessment (see my previous post) on highway mileage is likely to slightly improve with a shell.
And Congratulations on joining a great forum, welcome aboard!!! You already sound as though you will be a wonderful addition to the boards for future topics. We have some great folks who have contributed a lot of different ideas and mods, it's a great kinda commune here. Take care, keep as active here as you can in your spare time.
Gas mileage with a shell?
If so, did you notice the wind blowing directly on you if you were sitting near the tailgate? We hated sitting next to the cab, the wind caught by the tailgate caused dirt to blow back towards the cab and get in our eyes. 
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