Tonneau cover mileage increases - The 1947 - Present Chevrolet & GMC Truck Message Board Network

RapidRide2 · 10-03-2004, 01:23 PM

Are there any people out there that have had any "real world" mileage increases from installing a tonneau/ fiberglass cover??? Thanks to all who reply.

gchemist · 10-03-2004, 03:39 PM

Yes, I had a fiberglass cover. Then removed it for a soft cover. The fiberglass cover was custom made and was a little heavy for the 305. Though the guy I sold it to used it on a hot 350, he noticed the difference right away. For a ~70 mile trip 1/2 tank sure beats 3/4 of tank. I get 18 MPG with my 305.

screwballl · 10-04-2004, 02:19 AM

i have heard of big differences if you do alot of highway driving.. for regular city driving you only see 1-4mpg increase versus 5-10+mpg increase for highway use

Blue Beard · 10-04-2004, 07:30 AM

Don't know the mileage difference, but I've been running a hard tonneau for the past five years and seems like I don't hit the gas station near as often.

**N2TRUX** · 10-04-2004, 09:49 AM

It's a bit more hype that fact. I have had bed covers on 4 late model trucks now. Mots of them were put on within a few weeks of purchase. I always watch my mileage when my trucks are new. I do most of my driving on the highway and cruise 75-80 mph The average increase I see is 1-2 mpg....

76bonanza · 10-04-2004, 04:52 PM

I have heard the wind flow in a pickup bed is different then most would think and they only help a little and only at high speeds. Maybe someone who knows about this stuff will chime in.

PRUNEDA · 10-04-2004, 05:00 PM

I bought a SnugTop for my '89 and i didn't notice any mileage increase, what i did notice was that it rides different cause of the weight in the back. It looks good and everything.

Russell · 10-04-2004, 05:05 PM

I just took my tailgate off -- Much cheaper

SanitysBane · 10-04-2004, 07:44 PM

tail gate off actually screws up the air flow more than anything, there is a low pressure area right behind the cab, the air goes from the top of the cab and goes straight to the tail gate, causing a low presure area right behind the cab, i have no clue what it does with out the tail gate, but the major thing to have is that front air dam, that makes the most diff.

Russell · 10-04-2004, 07:54 PM

I've got a front air dam too

I can't see how taking the tailgate off would mess stuff up, air would flow through it rather than getting caught in the box. The cab will create that low pressure system behind it regardless...

SanitysBane · 10-04-2004, 08:14 PM

i remeber a long while back when some guys did a test and found that only thing that helped any was the air dam

cliffsta · 10-04-2004, 08:16 PM

if you think about it, the cab's height and general shape pushes most of the air up or flat and not really has a shape for air to go downward.

jimfulco · 10-05-2004, 02:07 AM

One of the Popular-Mechanics-type magazines (I think) tested some pickups years ago, & they said the best was with a camper shell that matched the profile of the cab, followed by a bed with a flat cover, followed by a bed with the gate down, and the bed with gate up was worst.

Throw a bag of leaves in the bed (without the bag) & drive around for a while. There will be a pile of leaves in the bed right behind the cab. They will swirl around like a horizontal tornado if you look while you're moving. Mine leaves a bigger pile with the gate up, so I figured air was flowing out more when it was down. Scientific, huh?

gchemist · 10-05-2004, 05:25 AM

SWB and LWB trucks have different wind characteristics. 88+ SWB trucks are better off with the tailgate up!! All LWB trucks and 87 and older trucks definately need help.

apstguy · 10-05-2004, 02:39 PM

I don't really see any mileage difference but I have a 305 that gets 10 mpg so I don't think I count...

Kas68c10 · 10-06-2004, 02:14 PM

I did not notice a difference in mine

*gn4u2c* · 10-07-2004, 11:46 AM

Hmm. seeing how I am usually driving with my foot to the floor sideways through 2-3 feet of mud. Guess I would see no improvement from a cover ?

10-03-2004, 01:23 PM	#1
RapidRide2 Registered User Join Date: May 2004 Location: Saint Louis Posts: 76	Tonneau/f/glass bed cover mileage increases Are there any people out there that have had any "real world" mileage increases from installing a tonneau/ fiberglass cover??? Thanks to all who reply. Last edited by RapidRide2; 10-03-2004 at 02:01 PM.

10-03-2004, 03:39 PM	#2
gchemist BAD BOW-Silverado XST Join Date: May 2000 Location: Senior Member from Austin, TX Posts: 6,431	Yes, I had a fiberglass cover. Then removed it for a soft cover. The fiberglass cover was custom made and was a little heavy for the 305. Though the guy I sold it to used it on a hot 350, he noticed the difference right away. For a ~70 mile trip 1/2 tank sure beats 3/4 of tank. I get 18 MPG with my 305. __________________ Gerardo a.k.a. Mad Chemist Silverado XST videos

10-04-2004, 02:19 AM	#3
screwballl Tonawanda 454 Join Date: Mar 2004 Location: Liquid Sunshine State Posts: 2,754	i have heard of big differences if you do alot of highway driving.. for regular city driving you only see 1-4mpg increase versus 5-10+mpg increase for highway use __________________ 91 Chevy Suburban Tonawanda 454 R2500 - SOLD!!! 04 Dodge Durango 5.7L Hemi 2WD, 24K miles (as of July 2011) In the past 30 years about 90% of Fords are still on the road, the other 10% made it home. -------------------

10-04-2004, 07:30 AM	#4
Blue Beard Registered User Join Date: Jan 2003 Location: Washington State Posts: 8,831	Don't know the mileage difference, but I've been running a hard tonneau for the past five years and seems like I don't hit the gas station near as often. __________________ 1970 Chev CST 2003 Harley Fatboy 1975 Chevrolet Step Van 1956 Chev Bel Air 1977 Blazer 2WD For Sale $3000.00 1978 Blazer 2WD For Sale $7000.00 1978 Silverado 2005 Monte Carlo

10-04-2004, 04:52 PM	#6
76bonanza Senior Member Join Date: Mar 2003 Location: St robert Mo Posts: 2,001	I have heard the wind flow in a pickup bed is different then most would think and they only help a little and only at high speeds. Maybe someone who knows about this stuff will chime in. __________________ 1968 c10 lowered 3" 4" 355/Th400 built by Hatfield racing in joplin MO

10-04-2004, 09:49 AM	#5
N2TRUX Happy to be here Join Date: Mar 2000 Location: Cypress, TX Posts: 39,021	It's a bit more hype that fact. I have had bed covers on 4 late model trucks now. Mots of them were put on within a few weeks of purchase. I always watch my mileage when my trucks are new. I do most of my driving on the highway and cruise 75-80 mph The average increase I see is 1-2 mpg....

10-04-2004, 05:00 PM	#7
PRUNEDA '87 Join Date: Jun 2004 Location: Katy, TX Posts: 632	I bought a SnugTop for my '89 and i didn't notice any mileage increase, what i did notice was that it rides different cause of the weight in the back. It looks good and everything.

10-04-2004, 05:05 PM	#8
Russell Professional Grade Join Date: May 2003 Location: Fort McMurray, Alberta Posts: 7,915	I just took my tailgate off -- Much cheaper __________________ 1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap)

10-04-2004, 07:44 PM	#9
SanitysBane Registered User Join Date: May 2004 Location: Lubbock, Texas Posts: 2,121	tail gate off actually screws up the air flow more than anything, there is a low pressure area right behind the cab, the air goes from the top of the cab and goes straight to the tail gate, causing a low presure area right behind the cab, i have no clue what it does with out the tail gate, but the major thing to have is that front air dam, that makes the most diff. __________________ '96 Nissan Pathfinder '02 Firebird Trans Am. '88 K5 Blazer

10-04-2004, 07:54 PM	#10
Russell Professional Grade Join Date: May 2003 Location: Fort McMurray, Alberta Posts: 7,915	I've got a front air dam too I can't see how taking the tailgate off would mess stuff up, air would flow through it rather than getting caught in the box. The cab will create that low pressure system behind it regardless... __________________ 1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap)

10-04-2004, 08:14 PM	#11
SanitysBane Registered User Join Date: May 2004 Location: Lubbock, Texas Posts: 2,121	i remeber a long while back when some guys did a test and found that only thing that helped any was the air dam __________________ '96 Nissan Pathfinder '02 Firebird Trans Am. '88 K5 Blazer

10-04-2004, 08:16 PM	#12
cliffsta Stepsides RULE Join Date: Jul 2004 Location: Pineville, LA Posts: 1,921	if you think about it, the cab's height and general shape pushes most of the air up or flat and not really has a shape for air to go downward. __________________ 1981 Chevy C10 Custom Deluxe Stepside 350 V8, headers, side exhausts, 3-speed auto SOLD 1980 Chevy C10 Custum Deluxe Stepside 305 V8, Edelbrock Performer Intake, Edelbrock 1406 600CFM 4-barrel, TH350C. Bent rod. SOLD 1984 GMC Sierra Classic Longbed 6.2L Diesel SOLD 2009 Kawasaki KLX-250S too many mods for this signature 1999 Honda Accord EX 4-cylinder, 17" Motegi Wheels 215/45/17 Sumitomo tires, Tein S-Tech lowering springs, KYB GR2 shocks, Acura TL 20mm rear swaybar, debadged, blackhoused headlights, Short-Ram Intake Cardomain of the Accord

10-05-2004, 02:07 AM	#13
jimfulco Registered User Join Date: May 2003 Location: Shreveport LA Posts: 3,170	One of the Popular-Mechanics-type magazines (I think) tested some pickups years ago, & they said the best was with a camper shell that matched the profile of the cab, followed by a bed with a flat cover, followed by a bed with the gate down, and the bed with gate up was worst. Throw a bag of leaves in the bed (without the bag) & drive around for a while. There will be a pile of leaves in the bed right behind the cab. They will swirl around like a horizontal tornado if you look while you're moving. Mine leaves a bigger pile with the gate up, so I figured air was flowing out more when it was down. Scientific, huh?

10-05-2004, 05:25 AM	#14
gchemist BAD BOW-Silverado XST Join Date: May 2000 Location: Senior Member from Austin, TX Posts: 6,431	SWB and LWB trucks have different wind characteristics. 88+ SWB trucks are better off with the tailgate up!! All LWB trucks and 87 and older trucks definately need help. __________________ Gerardo a.k.a. Mad Chemist Silverado XST videos

10-05-2004, 02:39 PM	#15
apstguy LED King Join Date: Jan 2003 Location: Sacramento, CA Posts: 2,087	I don't really see any mileage difference but I have a 305 that gets 10 mpg so I don't think I count... __________________ Tyler 1985 C10 305 w/ Bowtie OD TH700R4 3.42 LSD 202,000 miles 2006 Ford Focus ZX3 5-speed Stick 2016 Chevy Spark EV Gone: 2002.5 VW GTI 24v VR6 Gone: 2008 VW R32



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10-06-2004, 02:14 PM	#16
Kas68c10 Registered User Join Date: Apr 2000 Location: Freeland,Michigan,USA Posts: 312	I did not notice a difference in mine __________________ 1968 SWB Stepside, 250,pwr disc brake and tilt pwr steering, 5 spd tranny, HEI,Accel coil,K&N filter,Seat from a later truck with built in seatbelts, front and rear sway bars, moved gas tank to under the bed, headman hedders, new chrome bumpers,one wire alternator,Weber k550cub carburator...WORK IN PROGRESS, Freeland MI , Just bought a 72 Jimmy!!!!!!!!!!!

10-07-2004, 11:46 AM	#17
gn4u2c Account Suspended Join Date: Mar 2003 Location: southern pa Posts: 698	Hmm. seeing how I am usually driving with my foot to the floor sideways through 2-3 feet of mud. Guess I would see no improvement from a cover ?

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