Getting very bad Gas Mileage??????

[beclar]

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.

[Steve]

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?

[beclar]

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.

[Steve]

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.

[spoontoad]

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...

[modified04]

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

[modified04]

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

[Steve]

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.

[Hydramatic]

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.

[Steve]

You'd better watch those slick tires when it rains next to the guadalupe river! :-) You'll slide all over the place.

[quickzilverado]

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.

-Anthony

[silverado2500hd]

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

[fbirex]

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.

[silverado2500hd]

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.

[Prabie]

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.

Regards,

Pedro from Chile

[davelammon]

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.

[Prabie]

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.

[RichardG]

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

[rescueandheal]

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.

[Lesechang]

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!

[TrailLeadr]

being pushed empty over a cliff: 8.8 mpg
:lol: :lol: :lol: :lol: At least it's consistent.
I'm sorry to laugh. I do feel your pain in regards to low mileage on the suburban.

There are things that can be done to help you get better mileage, but you'll probably never see numbers that match the dealer's tag.

However if you shut the engine off before pushing it over the cliff you should be able to increase your mpg's. :)

[travieso1]

Hello I'm new here. I have a '06 Sierra Crew Cab 5.3, 4x2 w/3.73's. I bought it in late August and have about 5700 miles on it. Best and constant MPG is about 15.3. Mostly city, highway stays about the same due to the fact I drive about 75 mph, over the speed limit in Southern Cali (65mph). Except when on the 99 heading to Bakersfield (70 mph), then I jump to about 80mph...

[84fiero123]

First lets set the record straight,
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.

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.

EPA estimates are never right for any vehicle, except under their exacting tests.

Want more power, then you should have got the 454, or better yet you should have bought the V10 Dodge, a buddy of mine has one, he gets 6, that’s right 6 miles to the gallon down hill with a good tail wind, hell he said he gets 6 going over a cliff with the engine off.

You put tires on that will not even allow you to pass inspection in most states. Never mind the bigger the tire, the more meat on the road, the more meat on the road the lower the mileage.

All I see is someone who bought a truck and should have bought a Preus. Oh wait you can’t tow anything with a Preus. Then I guess you are stuck buying a a truck and the mileage they get.

Ask on any forum for any vehicle, car, truck, suv, Non of them get their EPA estimates.

You bought a truck, you got what you bought, try towing your boat with a Preus or any other car.

[unplugged]

My burb gets 10-11mpg, and I don't care. I'll drive it if gas goes to $10/gal. I didn't buy it for its fuel efficiency. I bought it for its utility. Whether I want to go banging around the desert, or take everybody to the beach, or tow the seadoo's to the river, or help a friend move a couch, the burb gets the job done. If I wanted economy I would have bought a Honda.

[Steve]

When driving the burban, I find that I don't care. I have a task to do and need to git r' done. When commuting to work mon-fri, I DO care about fuel economy, that's why I drive the little Cavalier --- it gets 30+ MPG and it's easy to park.

As for MPG stickers, all vehicles are the same. If someone has a lead foot and they have driving habits that cause more fuel to be burned ... they'd get 20 MPG in a Prius or a Vespa scooter. Even the supposed "fuel efficient" foreign cars still will seem similar MPG drops with the same driver.

[NHSilverado]

2005 Silverado 1500
Extended Cab 4X4
HO 5.3L
3.42's
P265/70R-17's

10,500 miles

MOD'S:

Gibson dual exit split rear stainless exhaust
Royal Purple Fluids( oil, front and rear diff's, coolant additive )
Undercover hard tonneau

I keep very accurate fuel logs so my MPG figures below are accurate( ie; miles driven divided by gallons required to fill ). I will also post my regular fuel blend MPG and winter fuel blend MPG. It is significantly different. I HATE the winter fuel they force on us. That combined with the longer warm up time to achieve operating temp in cold weather causes MPG to plummet.

Non Winter Fuel:
100% City: 15.5-16.5 MPG
Mixed City & Highway: 17-20 MPG( depends on how much is city vs highway )
100% Highway: 20.5-23 MPG( highest actual to date = 22.7 )

Winter Fuel Blend:
100% City: 13.5-14.5 MPG
Mixed City & Highway: 15-17.5 MPG( depends on how much is city vs highway )
100% Highway: 18-19.5 MPG

The figures above are the averages I have seen consitantly in the 10 months I have had the truck. Obviously there can be a .2 or .8 in there. Rounded off to the nearest .5.

I have been very impressed with the MPG from this truck. It has met for the most part, and even exceeded at times, the EPA ratings for it of 15/19. Definitely the closest to those ratings of any vehicle I have owned. When you can get almost 23 MPG, even if it is all highway, out of a full sized V8 4WD truck that is great.

I should note however that I drive like an old man. I am only 39 but I drive very conservative 99.9% of the time. I will get on it a bit at times when entering a highway, and I do open it up good to pass someone, but otherwise I take it easy. I do not exceed 65 MPH on the highway( actually 62 MPH in CC gets me the best MPG - I stay right so you crazy lead foots can get by me :tongue: )and I accelerate easy from stops. Those two acts alone give me a good jump in MPG over those who have to hammer it all the time and go 80 MPH.

Oh, and when I went from the Goodyear Wrangler ST A/S( car/highway tread )stock tires to the more aggressive Bridgestone Dueler AT Revo I saw a definite small loss of MPG despite keeping the stock tire size. Doesn't take much to drop MPG.

[Steve]

2005 Silverado 1500
Extended Cab 4X4
HO 5.3L
3.42's
P265/70R-17's

10,500 miles

MOD'S:

Gibson dual exit split rear stainless exhaust
Royal Purple Fluids( oil, front and rear diff's, coolant additive )
Undercover hard tonneau

I keep very accurate fuel logs so my MPG figures below are accurate( ie; miles driven divided by gallons required to fill ). I will also post my regular fuel blend MPG and winter fuel blend MPG. It is significantly different. I HATE the winter fuel they force on us. That combined with the longer warm up time to achieve operating temp in cold weather causes MPG to plummet.

Non Winter Fuel:
100% City: 15.5-16.5 MPG
Mixed City & Highway: 17-20 MPG( depends on how much is city vs highway )
100% Highway: 20.5-23 MPG( highest actual to date = 22.7 )

Winter Fuel Blend:
100% City: 13.5-14.5 MPG
Mixed City & Highway: 15-17.5 MPG( depends on how much is city vs highway )
100% Highway: 18-19.5 MPG

The figures above are the averages I have seen consitantly in the 10 months I have had the truck. Obviously there can be a .2 or .8 in there. Rounded off to the nearest .5.

I have been very impressed with the MPG from this truck. It has met for the most part, and even exceeded at times, the EPA ratings for it of 15/19. Definitely the closest to those ratings of any vehicle I have owned. When you can get almost 23 MPG, even if it is all highway, out of a full sized V8 4WD truck that is great.

I should note however that I drive like an old man. I am only 39 but I drive very conservative 99.9% of the time. I will get on it a bit at times when entering a highway, and I do open it up good to pass someone, but otherwise I take it easy. I do not exceed 65 MPH on the highway( actually 62 MPH in CC gets me the best MPG - I stay right so you crazy lead foots can get by me :tongue: )and I accelerate easy from stops. Those two acts alone give me a good jump in MPG over those who have to hammer it all the time and go 80 MPH.

Oh, and when I went from the Goodyear Wrangler ST A/S( car/highway tread )stock tires to the more aggressive Bridgestone Dueler AT Revo I saw a definite small loss of MPG despite keeping the stock tire size. Doesn't take much to drop MPG.

What were you doing when you got the 22.7 MPG?

Also, I have heard that some big rigs are looking at some new tires that are supposed to give about 5% better gas mileage. That adds up for long-haul truckers.

[NHSilverado]

What were you doing when you got the 22.7 MPG?

Also, I have heard that some big rigs are looking at some new tires that are supposed to give about 5% better gas mileage. That adds up for long-haul truckers.


What do you mean? RPM, speed, type of driving?

Was all highway. I was in CC going between 60 and 65MPH( average around 62 )the whole time. RPM's hover around 1500-1700. Filled up at a gas station that is just a few hundred yds from the highway entrance before I left and when I got back. Had maybe 10 miles total, counting the city roads to my friends house, that was not highway. Went 134 miles on 5.9 gallons of gas( 22.711##### MPG )

[unplugged]

I drive an 06 4x4 for work and I make frequent stops and let it idle sometimes for an hour or more and I get 11-12mpg consistently.:cool:

[quickzilverado]

Well, its been almost a year since I posted about my gas mileage...and I've done a few more mods to my truck. Total mods are:

-K&N 77 series intake
-50 series Flowmaster
-NGK plugs
-Mobil 1 synthetic oil
-Wait 4 Me custom PCM tune

I've also upgraded to 285/75/16 (33") tires...compared to 265s I had before.

I know what you're saying about winter blend...it sux! I'm getting probably about 13.5-14.0 with 80% city and 20% highway. In the summer I get about 16 mpg w/ 80% city and 20% highway. Funny thing is my span doesnt change much. The best I've seen is 19 mpg driving to spokane...but I also went racing and such too :P I'm very very hard on my truck...I dont drive it nice....

BTW, I have a 4.8 V8 in an extended cab short box w/ 4x4 and 3.73 gears. Also, I recommend a PCM tune...it really helped pulling my boat and I gained a couple mpg (then it went away when I got my 285s...hehe).

-Anthony

[GWAGON_99]

I get anywhere from 11.5-12.8 mixed city to highway. The best I have ever seen is 15.4 when I drove it to South Carolina with no trailer and completely empty. I have 5.7 V8 and 3.73 gears(4WD). Unfortunately I drive about 25-30K miles a year...not good with rising gas prices! My worst tank was driving from Delaware to Texas towing My Jeep and I had the inside of my truck completely loaded down(one item was a large safe!) With 4hrs of idle time (me sleeping at a truck stop) I got 6.3mpg!!!

[98BuickRegalGS]

Best way to improve your MPG is make sure your trucks in tip top shape.

New O2 Sensor,New Plugs, New Maf, Do a top engine clean and run a good cleaner like Sea Foam or Berryman throughthe gas tank and you'll pick up a few MPG :great:

[98BuickRegalGS]

Oh and to add to this, my parents have a 5.9 Durango and that thing gets 10MPG no matter what. The dealer sticker said 13/17.

So you people with Suburbans getting 8-10, just smile knowing a much smaller and boring Durango gets about the same

[TrailLeadr]

Nice supercharger!! Factory, or aftermarket?

You should add that pic to our "Guess the engine thread"

http://www.gmtruckclub.com/forum/showthread.php?t=4008&highlight=game+gear

[98BuickRegalGS]

Nice supercharger!! Factory, or aftermarket?

You should add that pic to our "Guess the engine thread"

http://www.gmtruckclub.com/forum/showthread.php?t=4008&highlight=game+gear


Thanks! It was supercharged from the factory, responds very well to mods :cool:

[Steve]

bump this popular thread.

[95CTburb19]

I get 10 in my sierra 5.7 vortec. I think I may have 4.10's though.

[Steve]

just curious if anyone has seen any great improvements in MPG from any mod they have done?

[finalday7]

Don't feel too bad. My new 07 is averaging 11.5 MPG

[JayMack75]

I'm getting around 8-9 city and 13 (if i am lucky) highway. It did jump when I installed my hypertech programmer.

[finalday7]

I'm hoping next couple of weeks to get a Hypertech Max Energy Programmer. I'm keeping good track of my miles so I can compare the 87 economy tune to see the benefits. It has a 30 day money back guarantee so If it doesn't deliver what i'm looking for the place i'm getting my truck dynoed at next month will do a complete custom tune for $180.

[Steve]

I'm hoping next couple of weeks to get a Hypertech Max Energy Programmer. I'm keeping good track of my miles so I can compare the 87 economy tune to see the benefits. It has a 30 day money back guarantee so If it doesn't deliver what i'm looking for the place i'm getting my truck dynoed at next month will do a complete custom tune for $180.

Keep us updated on that.

[armand71]

I find it depends on which gas I use. There seems to be a noticeable difference between fuel companies for my truck anyway. My Tahoe seems to sip Esso gas but will go through a tank full of Chevron twice as fast....well not that bad.

[Outrider]

My 99 Sierra EXT CAB 4X4 is getting 12mpg city/hwy mixed in winter. Hope to see it increase to 15-17mpg next summer and that's being optimistic. My sonoma ext cab 4.3 V6 2wd was getting average 19 to 20 mpg. And my sonoma 4cyl 2wd was getting average 23 to 25mpg with a 5 speed. My 07 civic 5 speed is getting 35-38mpg.
Hope this helps. It all seems to be relative.

[crane3447]

I getting about 20 mpg highway with a 5.3 in my '04. I did some basic mods and now I get about 2-3 mpg better then stock with about 40 xtra hp and tourque.

[black jack]

Heres another interesting ? what type of gas are you using? Iknow the E85 withh get 5mpg less than reg. gas. Just woundering if that might be part of problem.

[30 Yr GM Tech Burn-out]

I think I know the noise youre talkin about. Back in 03, When I traded my 98 2wd for my 2002 4x4, I noticed a Snapping noise when I shifted from rev. To foreward. Almost sounded like the driveline had a crack in it. I was working for a Major Dallas area dealership at the time, and one of my best buds is a 25year+ master tranny-man. He told me the same thing. Its normal for a 4x4..(per GM)...I still didnt think we should be producing this kind of noise. about 5 mos ago I noticed a squeek noise when backing up....checked my u-joints, sure enough. The back one was trashed.changed it and I havent noticed the snap since..?? My truck only had 75k on it at the time. allittle soon for a u-joint... Ill keep listening!

[30 Yr GM Tech Burn-out]

?? 6.0s are notorious for crappy mielage.
Are you SURE yall have the SAME truck? Same maint done... Gears- Tire size and same fuel type (brand of gas) TIRE PRESSURE!! Air filter! Make any home repairs? Did ya fall into the Miracle spark-plug thing and change from OEM? If so, Put them back in.
If alls the same....I suggest you switch out and see if your bud can get the same out of your truck.
Lots of times its driving styles!
Remember! with a 6.0 in a heavy truck.....It takes Energy to make Energy!

[Steve]

Lots of times its driving styles!
Remember! with a 6.0 in a heavy truck.....It takes Energy to make Energy!

Thanks! Wanted to bump this old but popular post.

[gearhead952]

I have an 03 2500 6.0 and utility bed full of tools,and get about 8-9 mostly in town,but i feel like it should be a little better.

[jiujitsu]

haha im new here and i was wondering why mine was so bad on gas(05 4x4 silverado 1500) ..i drive a lil agressive but no matter what i did i cant get anyhting better then 14 if that..atleast its not just me hehe j/k:na:

[steves86ta]

Heres my look on it. I just got my 08 silverado, it is a 5.3, 3.73's, locker, and the 20's. It is also an extended cab and short bed. Ive put about 1100 miles on it (bought it new) about 80% highway 20 city, and i get between 16-18 driving 80 all the time. And around town it is pretty spirited driving. The car i traded in on it was a 2006 pontiac g6 GTP with the 3.9 engine. This car got if i was lucky 21 mpg, it had a CAI and a full exhaust. Didnt matter how i drove it it got 20 on the average. So in my case im getting 2-4 less miles per gallon, but i have a truck and the usefullness of a truck pays off everytime. My dad has a 2005 silverado, 5.3 crewcab 2wd and he gets about 17-19 average and with me driving it it gets about 15-17 average. So drivers do make a difference, but when you sit down and look at it, the gas mileage isnt bad for something that weighs two and a half tons, and has 300 horsepower. I personally cant complain. Now my friends f-150 supercrew he can complain hes lucky to get 13 on the highway

[adidasboy918]

I get around 18-20 miles on the freeway depending on if i gun it to get away from people and i wanna say around 13 miles here in town going from home to work up hill.

[Steve]

bumping. This thread has lots of good ideas in it.

[Hamelfire]

IS it possible to get worse milage in the winter? 08 2500 CC 6.0 motor. When it's colder I get worse milage then when its warm. Does the air temp going into the motor make a difference? Also do they switch blend of gas durning the winter?

[ippielb]

Cats / O2 sensors? Seafoam?
IS it possible to get worse milage in the winter? 08 2500 CC 6.0 motor. When it's colder I get worse milage then when its warm. Does the air temp going into the motor make a difference? Also do they switch blend of gas durning the winter?
Yes, you do get worse mileage, i heard somewhere that the fuel doesn't fully ignite like in warm weather, or something like that.

[amd's chevy]

My gas mileage has been terrible as well. Partly due to the larger 35s I have for tires but also I just changed my fuel filte and the old one was filthy. I noticed the RPMs while on highway is lower plus I have alot more acceleration. I haven't gone threw a tank of gas yet since the change but I expect a substantial difference in my gas mileage. I'm going to change my filter each spring for now on.

I have '01 with 5.3 L.

[chiefbkt]

I don't drive my truck much now, but when I used it for my daily driver I would average 17-18 mpg highway and that is with the cruise set on 73-75 MPH. When driving around town I get 14-16mpg, which isn't bad. I have the 5.3L, ext cab, 4x4, with a cap on it in the winter and tonneau cover in the summer...gets the same mpg's with either one on.

[black jack]

let me ask this question what is the e85 rating. is it 10% ? i know you will get 5 miles less than the reg. gas we used to put in our vehicals.