GM Truck Club Forum banner

Getting very bad Gas Mileage??????

30936 Views 58 Replies 36 Participants Last post by  black jack
Hi we own a silverado 2WD, V8. It is getting horrible gas mileage, maybe 12 or 13 MPG. Has anyone else been having this problem. Dealer said nothing was wrong, but obviously it should be doing better than this.

Any suggestions would be appreciated.
1 - 20 of 59 Posts
Hi, just a few questions.

What year? What size v8? How many miles are on it? Basic questions. ALso, what do you do with it?
It is a 2005, V8, low profile. Driving like we would any vehicle. Not hard on it, and never drive over the interstate speed limit. Have pulled a trailer with it once, which is partly what it was bought for and it handled fine, but has never had good gas mileage. Have owned trucks before, and this has never happened. The one odd thing is that when you are slowing down, or trying to break it sounds like the engine wants to race. The dealer noticed the engine does step up a bit, but that is all he said.

With gas prices the way they are we don't need this now.

Thanks for any help you can offer.
Do you have the gear ratio? This is a little bit low for a V8 that's just being driven around town, etc. I'll have to check to see what the average MPG is for your truck.
I to am getting crappy mileage. I have a 2003 2500HD that gets about 10mpg, and the dealer says this is normal. I know it's not because my buddy gets 13. Mine has 20,000 miles on it and has a 6.0 V8 Stock tires, no engine mods...
i work for a chrysler dealer and the window sticker is no where near correct you wont get anything close to it the formula they use to determine the fuel mileage is very very old from when the speed limit was 55 everywhere and there wasnt as much stop and go traffic as there is today
my 04 1500 has a horrible drive line snap when the tranny upshifts on lite acceleration the dealer says they cant fix it on any of them and that they all do it is this true and does anyone elses 1500 make a differential noise when the truck is in four wheel drive at slow speeds on light accel
There are a lot of variables as well. For instance, how hard do you hit the gas off the line? Do you drive a lot over the speed limit? Open bed or tonneua cover? Etc. My '78 454 suburban will get close to 10 if I drive right.
Yeah, this sounds familiar. I get pretty crummy gas mileage, but I could care less. I think so far I've averaged around 16 mpg, mixed highway and city driving, with the occasional gunning of the engine at my friends at work, but other than that, fairly sedate driving due to my rear tires being pseudo-slicks. To be truthful, I'm surprised that the Silverado gets as good gas mileage as it does, what with a fairly powerful engine, a heavy body, and a four-speed auto, all connected to a 3.42 rear-end. Very surprised.
You'd better watch those slick tires when it rains next to the guadalupe river! :) You'll slide all over the place.
Heya, I just joined...I have a 2002 Silverado 1500 ECSB 4x4

I got pretty crappy gas mileage this last winter but it still averaged about 14.6 driving all city, and I am NOT light on the gas. It has the 4.8 liter with 3.73's in the rear.

Only mods I have are a K&N drop in air filter and a Flowmaster 50 series truck and SUV w/ 3" rear section.

Lately when I'm not pulling my boat, I'm getting around 15.5 all city...but it should go up once the weather gets warmer, its been about 55-60 degrees here lately.

I'll let everyone know what gas mileage I got when I pulled my boat, I pulled it on a 40 mile trip up hills, then I pulled it to the local marina the other day...from the looks of the gas guage and trip meter I'll probably get about 14.5. Not too bad for a 4.8 which is very doggy...haha.

I have a 2002, 2500HD with 8.1 liter. I get, driving to work daily, about 10 to 11 mpg. Do you think that any type of tonnaue cover over the bed would increase fuel milage? With gas prices like they are I'll do anything to help.
Thanks for your replys
Hasn't anyone watched Myth Busters. They had a show where they tested having the tailgate up and down, and the truck did better with the tailgate up. So why would a Tonnaue cover help if it its better to have the tailgate up to begin with. I know, it doesnt make sense. Oh yea, with the summer months comming... Myth Busters also did windows down vs. A/C and they were about the same. Actually the A/C might of gotten like .1 or .2 MPG better.
My truck has the 8.1 liter. And I notice a big difference with A/C on or windows down. I wanted to hear from someone who actually has a tonnaue cover installed to see if they have noticed a difference.
Hi: Gas comsuption is a function of:

a) The weight of your vehicle and how much you accelerate to reach certain speed :twisted:
b) Frictional forces inside the motor and gears :?
c) Aerodinamical Drag :shock:

For a) as long as you drive a heavy vehicle and use to accelerate even if you see the light turning to red ahead of you, you will have bad Gas Mileage (BGM). Move to a lighter vehicle or drive more softly and slowly to save gas. 80% or more of the power excess required to accelerate fast is spend in the form of heat at your radiator!!! Did I mention heating your brake pads also?

For b) you have the chance of investing in a better oil. Spend some time in researching for oils that present gas saving proprieties.

And for c) you have to notice that every time speed doubles air resistance to movement doubles twice. i.e. your consuption at 60 mph will be 4 times the one you have at 30mph.

Abnormal conditions as tires underinflated, brakes misadjusted, damaged spark plugs, etc. can cause you BGM also. Check your air filter also because some ignition systems compensate the lack of air adding more fue that won't be burned becuase of the clogged filter.

:idea: Also note that 4x4 use much more fuel than 4x2 (Do you remember when was the last time you really needed 4x4 traction?)

With my 5.3 L 2002 4x2 Crew Cab in city/highway my mileage use to be 15.6 MPG. The best engine in terms of mileage for Silverados is the 5.3L.


Pedro from Chile
See less See more
HIgh Gas comsumption

First lets set the record straight,

when they set the standards for EPA fuel efficiency , they used driving standards that are way out of line with whats normal driving. Your EPA sticker will be anywhere from 30-50% off.

If I'd have known I'd never bought my 1/2 ton silverado 4x4. I have been getting approx. 10-12 MPG since I've owned it.

I was getting 13-14 MPG when I bought it with stock wheels/tires. Since putting on a lift kit and 35 inch wheels I get approx 1-2 MPG less.
Chevy says everything is fine, cause they are brain dead and cannot perform a diagnostics without the use of some computer. Computers' are ok, actually necessary to diagnose new engine and transmissoin problems . But.. What if the problem lies outside the scope of the computer sensors. What if the problem in this case is not an actual problem, but more of an efficiency issue.

I think Chevy is holding back something they all know. The Silverdado is a gas hog. THe EPA sticker was way off.
People were misled into thinking they might be able to actually commute in a vehicle of such and only found out they have to park it most of the time.

I use mine to tow a boat. When I'm towing I get probably 8-10 MPG.

I should have bought a 3/4 ton truck if I would have known it would perform as such.

I was led to buy my truck because I was told it would tow my boat and perform reasonably with tighter steering.

Again, for those of you who bought chevy truck, give it up. ITs a hog.. Unless there's someone who can say what one could do to improve on the mileage sell it. Get a diesel.

Dual exhaust?
High Perf Computer chip?
New Intake?
Cam timing?

hmm. I dont think so..

One frustrated Chevy owner. I think I sell mine and get something that at least will tow with power while its sucking down the fuel.
See less See more
If you wanted a economy car you made a BIG mistake when you choose a 4x4 silverado, specially when you lifted it and changed the tires for wider ones. What were you thinking? It's like getting married with Paris Hilton and claiming because the girl use to eat caviar and wear Louis Vuiton Bags.

You did all the things the manual recommend not to do to get better economy.

Do you think that changing your Silverado for a F-150 will improve your mileage?? Let me smile.
1999 2500 2WD 6.0L K&N airbox & filter 4L80E trans:

not towing: 11.0 to 14.5 city
13.5 to 17.9 highway @65 MPH

towing 26' travel trailer: 9.0 to 12.6 @ 60 MPH
Average over 7500 miles: 9.8 MPG
I have a 03 silverado with a small 8 in it. I have a cover on the back but spend more time in the gas station than on the road it seems. It seems so lite that I have to idle off any red lite or stop sign so I don't spin the tires. Is there any real solution to this. I would be up for any help close to trading it in.
1976 454 V8 Suburban 2wd

using MaxLife oil: 8.8 mpg
using 10-30wt oil: 8.8 mpg
with old spark plugs after failing emissions: 8.8 mpg
after complete tune up and again fai: 8.8 mpg
not towing: 8.8 mpg
towing: 8.8 mpg
towing a full load uphill in a hurricane: 8.8 mpg
being pushed empty over a cliff: 8.8 mpg

God I wish someone would make a fuel-cell retrofit kit!
1 - 20 of 59 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.