Another MPG rant !!!!

[mabr]

Alright to those that follow this forum you know I bought a new 2011 Silverado this spring. If you remember I said I wasn’t happy with the gas mileage after a month or so. Some said let it break in and it will get better once it’s broke in. Well it now has over 10K on it and I’m still getting 12-13 mpg. I’ve tried driving it easy, driving it hard, pulling my fiberglass boat in tow mode and out it doesn’t matter it gets 12-13 no matter what I do. I’ve reset the average mpg monitoring gauge while on the highway set on cruise @65, doing this it averaged 17mpg over about 60 miles of flat highway driving. That’s the same 4 mpg less than it should be getting! The active fuel management is working, or at least the gauge shows it goes into 4 cyl when cruising. I use regular unleaded NO E85. I haven’t tried any higher octane yet. FWIW It has the 5.3 liter engine, axle is 3.42 ratio, Z-71 package 18 inch tires.

I’ve had it in to the dealer for normal service and I mentioned it to the service writer, he said the same thing as others on here have said, let it break in and it should get better. That was 2500 miles ago. I’ve talked to other Chevy owners who have the same truck same year etc. and they all are getting in the high teens. Why the heck isn’t mine?

I know its A TRUCK I shouldn’t expect great gas mileage but I bought it based on the sticker saying it should get between 15-21mpg and combined being 17! With 10k miles in less than 4 months I do my share of driving and a 4 mpg increase adds up to over $600.00 I wouldn’t have spent based on $3.50 per gallon average. Folks that adds up over the life of a vehicle!

Would you be happy with this if you owned it?

I’m going to take it in to the dealer and have them look into it. BUT my worry is, based on my research on a Chevy forum there have been a “FEW” that have had this same issue and had little luck with it being corrected by GM. GM has tried, they have put monitors on those vehicles set computer for various things but judging by the forums it didn’t change much if anything. How can one truck be so much worse than the exact same truck? I hate this, I like this truck. I like the looks, the drive, the ride everything except the gas mileage.

This IS a whining thread I know so please don’t start with the QUIT YOUR WHINING I’m not going too!!! I just don’t believe I’m asking too much when I see most others getting more mpg than mine when I know It’s not how I drive it.

[Jeremy airjer W]

What do you get for mileage with the cruse set at 60mph and 55mph? You will never get the mileage you think you will get with the cruise set at 65 or 70. I get the best mileage between 55 and 60. It will drop 2 mpg if I am in the 65 to 70mph range. If I have anything behind me, trailer, boat, loaded boat, loaded boat and loaded box I get 4 - 5 mpg less. If I drive into a 30mph headwind loaded down with a boat I get 9-10mpg less.

The first thing I would do is see if your vehicle is capable of reaching its intended best mpg rating by driving the 55 and 60 mph speeds. If it doesn't than you have a legitimate argument.

[Macgyver55]

This IS a whining thread I know so please don’t start with the QUIT YOUR WHINING I’m not going too!!! I just don’t believe I’m asking too much when I see most others getting more mpg than mine when I know It’s not how I drive it.

You probably already do, but make sure the tire pressure is at the higher end of the spec on the drivers door jam. In addition use quality gas, I personally wont use Holiday gas as it really does decrease the mileage on my Avalanche. Probably the main factor is driving style which is huge when it comes to mileage. I have always thought I was a decent driver, surely a heavier foot than some, but less than others. But, after having let my daughter use the Avalanche for a couple weeks, the average mileage was 3 MPG better than what I normally get. I've tried "driving nice" and using the mileage display to help but to no avail. I get 14 to 16 (not pulling a trailer) all the time... she got 18.6.

No explanation other than warning her if she wrecked it, she owns it.... or I'm just a heavier foot!

[certified jumbo]

Unless i drive about 55 mph, never stop or excellerate i've never gotten what the vehicle says you should get!! Can be frustrating but thats the way it works imo.

When i shop for vehicles i always take 3-5 mpg off what they say. I always tell the car salesman i take off about 5 mpg what they tell me, they typically laugh and agree. Rarely do people drive in the "perfect" conditions to reach those numbers.

[goblueM]

I've tried "driving nice" and using the mileage display to help but to no avail. I get 14 to 16 (not pulling a trailer) all the time... she got 18.6.

No explanation other than warning her if she wrecked it, she owns it.... or I'm just a heavier foot!

A big one is coasting - saves your brakes too. I always coast to red lights, stop signs, etc. We're programmed to drive at normal speed all the way til near a stopping point, then brake. You'd be surprised how far you can coast, even though it feels like you are going way too slow

[ASMOLEY]

What kind of tires do you have? Factory rims?

I got new tires last fall went from an all season to an all terrain. Not only are they more aggressive tread but they are an E rated tire. That is an extra 200+lbs in rubber... Lost a few MPG but haven't been stuck yet

[chasineyes]

Amen!! Especially when you can see traffic stopped a 1/2 mile ahead and people are still zooming by at 65, knowing full well in 10 seconds they will be down to 5.

[Jeremy airjer W]

Agreed, Coasting can be a huge boost to overall fuel economy!

[leech~~]

MA

Have you talk to anyone about doing a trany reprogram? They maybe able to adjust the shift points and get a little better on the top end?

Check this one out. Edge Evolution CTS Programmer - Color Touch Screen - V8 Engines - Chevrolet Silverado, 2011

[Whoaru99]

I'm confused...your 12-13mpg is pulling the boat or straight up highway driving (non-towing) or combination city-highway and is that towing or not towing?

[Lip_Ripper Guy]

If you have it in your area, try filling up with 91+ octane non-oxygenated, to see if it makes a difference. It has made a huge difference in my last 2 trucks. I found that I get the best mileage with 91-93 octane non oxygenated, and second best with 89 octane from Casey (same price as 87). If I fill up anywhere else, I see a drop of 2+ mpg.

[mabr]

Jeremy airjer- I’ll try and find somewhere where i can set it at 55 for highway speed but that’s pretty hard to do anymore lol. Most are 65 anymore.

McG- Im gonna let the wife take it to work and see what she gets. Like i said in the older post, I know I’m heavy footed but I have intentionally driven like and old lady and it hasn’t mattered.

Certified- LOL I hear that, but others ARE getting 18 mpg that is what is frustrating.

Tires are stock Bridgestone’s, I also have the tire pressure monitoring device on it so pressure isn’t the issue

Leech, that would be my last resort. I want the GM to tell me that needs doing. OH I left you a voice mail to, not about this, about fiberglass work

Whoareyou- 12-13 is an average of all driving. Just truck running down highway unloaded on cruise @ 65 i got 17mpg. I also got almost 12mpg pulling my 20 ft boat to Texas and back! That was doing 75-80 at times.

LILRipper I may try that in the long run.

[CJH]

If you have it in your area, try filling up with 91+ octane non-oxygenated, to see if it makes a difference. It has made a huge difference in my last 2 trucks. I found that I get the best mileage with 91-93 octane non oxygenated, and second best with 89 octane from Casey (same price as 87). If I fill up anywhere else, I see a drop of 2+ mpg.

The lack of ethanol has the biggest impact on your mileage gains, and then possibly the octane depending on what engine you have. BTW, that's illegal to regularly use that in your vehicles. No ones going to tell on you , but that's legal only for classic cars, boats and small engines. Generally you also pay more, so it may not Net out to much of a gain.

Right off the bat here in MN we lose approximately 10% off the posted MPG's due to the 10%ethanol we have in our gas, so make sure to factor that in. I'd make sure I am doing everything that the manufacturer recommends in terms of break in, maintenance, tire pressure, etc.. If you are doing all that stuff and its still not right, keep going back to the dealer and have them checking everything.

Not sure if your truck has one of the GM "learning" tranny's, but if you drive aggressively it will learn that and then essentially copy the behavior to some extent. So obviously how you drive has an enormous impact as well. Remember that HWY number is driving the speed limit, so if you go over that, it will drop.

Good Luck, hope you get it figured out.

[goblueM]

Jeremy airjer- I’ll try and find somewhere where i can set it at 55 for highway speed but that’s pretty hard to do anymore lol. Most are 65 anymore.

You aren't required to drive the posted speed limit you know! Feel free to ride along at 55 even if the speed limit is 65

[Scott K]

Higher octane isnt really going to help you out much here in MN. Maybe if you were 6000+ feet up, unless your vehicle is designed to run on higher octane. Like the Ecoboost engines.

Ethanol gets about 20% less fuel economy, so being there is only 10% ethanol mixed in the gas, you cant subtract 20% from it.

So comparing the 10% mixture here in MN, you get about 1% less economy with 10% blend. But for states without the blend, they charge more for the additives to get the fuel to pass emissions, so the fuel actually costs more. So dollars per mile of fuel, the 10% blend is cheaper.

[tonkapat]

I have the same truck as you. Last week I went up north with the ac on high 65 to 75 mph most of the time got over 20mpg for 500 miles. This past weekend took the boat to mille lacs got 15 going 75 into the north wind going up. Everday around town 16 to 18. I don't know that I could make the truck get 12 mpg. I feel i'm hard on it already. good luck keep trying to figure it out

[Whoaru99]

Higher octane isnt really going to help you out much here in MN. Maybe if you were 6000+ feet up, unless your vehicle is designed to run on higher octane. Like the Ecoboost engines.

Ethanol gets about 20% less fuel economy, so being there is only 10% ethanol mixed in the gas, you cant subtract 20% from it.

So comparing the 10% mixture here in MN, you get about 1% less economy with 10% blend. But for states without the blend, they charge more for the additives to get the fuel to pass emissions, so the fuel actually costs more. So dollars per mile of fuel, the 10% blend is cheaper.

By the numbers E10 (90% gas + 10% ethanol) has roughly 3.4% less BTU per gallon than pure gasoline. That should be the worst case difference you'd see in mileage between the two.

[Whoaru99]

FWIW, I've put about 40k miles on a 2010 Dodge Ram 1/2T 4wd extended cab with the 4.7L engine and I typically get 17-18mpg on the highway. Someone borrowed it from me and upon return commented they were impressed by the 20mpg they got. Go figure. Almost always driving style/habits accounts for the biggest difference in fuel economy between similar vehicles.

[SkunkedAgain]

I have the same truck as you....I don't know that I could make the truck get 12 mpg.

I think that you just made the OP cry!

[Powerstroke]

First and foremost, you cannot trust the trucks gauge for accurate mpg readings. Unless you're hand calculating your mpg you don't know what you're getting. My truck MPG gauge is frequently off. After checking my truck with a gps and calculating my data by hand I have a better understanding of my actual mpg numbers.

Also, unless you know someone personally, you can't trust what other people list online as their numbers. I would take 10% off of their numbers too.

[Whoaru99]

My numbers are pretty solid. I didn't pick the truck, didn't buy the truck, nor do I have to pay for gas or maintenance so I drive it as conditions merit, with zero reason to brag or sandbag mileage. It'll be driven roughly the same amount regardless if it got 10mpg or 30mpg.

It does drop back a fair mount on E85 though on the few times I've tried it, but I don't use it enough to give a good accounting.

[aanderud]

...

Just truck running down highway unloaded on cruise @ 65 i got 17mpg.

...

Wow. If you can get 17 mpg at 65 mph, I'm going to just about guarantee that you will get the rated 20 mpg using non-ethanol gas using your cruise control going 55 mph on flat ground without wind. That being said, I don't think you have a legitimate gripe here. Don't underestimate the difference in mileage that 10 mph is going to make -- these things are essentially the least aerodynamic vehicles made, and wind-resistance goes up exponentially with speed increases. Even my Impala will see a 3 mpg increase in mileage when I reduce my speed from 70 mph to 60 mph....I can't imagine your truck would be less than that.

Try a long trip at 55 using your cruise control (and try to stay on a 4-lane freeway so that you're not stopping and re-accellerating) and report back with your results.

[Scott K]

My truck at 75mph gets about 14, at 60mph, I get 18.

[mabr]

Alright, yesterday I made a trip down to the cities. About a 40 mile trip one way from my house. Headed south on hwy 65. Speed limit is 65 until you get around Blaine, hwy 610 to 252 then on 94. Doing 60-65 without cruise, no jack rabbit starts I got 21.5 or something close to that. Once I got to the traffic lights forget it. Was probably averaging (ON INSTANT GUAGE) around 12-13. After making my trip down and back gauges says I averaged 17.5 mpg.

So I guess im stuck with it. I’d say if I drove 5-10 miles less than the stated speed limit I could get the average 17 they claim. It’s just frustrating hearing others who get better mileage and drive similar to the way I drive. Powerstroke, I looked at the one guys average gauge and it said 18 something, I seen it with my own eyes. As far as doing the math, Ive done it both calculations were the same. I was REALLY surprised about that.

[Whoaru99]

The average published by the mfg is based on a certain mix of highway and city. If you have more city or your city has more or less stops, etc. then the average may not be the same.

Frankly, it sounds pretty normal to me for my experience with similar powertrains.