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Chevy Silverado and GMC Sierra Real World MPG Numbers

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  • mike537mike537 Posts: 4
    edited November 2010
    hello I own a 4.3L short bed silverado work truck with the 5 speed. When the truck was new (4250 lbs) my real life mileage was around 19-20 average mpg. The worst I ever recorded was 16, and the best was 23.5 with all highway driving at 60mph.

    Now I have upgraded the rear end from 3.23 to 3.90 and installed a supercharger. My average gas mileage with the supercharger was 16.5 mpg just highway. I then added an intercooler and took off 300lbs of weight and my total city/hwy averages 18mpg. On a full highway trip I will average 23mpg with this setup at 60mph. But I can also drain a full tank of gas in less than 2 hours if I'm really on the gas with this setup, the worst I have gotten was 11 mpg all city driving with a lead foot.

    The stock 3.23 (or even 3.42) gears for the v6 truck in my opinion does hurt gas mileage. These trucks are not aerodynamic, and any driving above 60mph will start to decrease mileage significantly. Problem is when they add a 3.23 rear the v6 truck is taching around 1500rpms in overdrive, and there is too much throttle work needed to maintain your speed up hills and in traffic. Chevy would have done better with either a 3.08 rear so it would tach low enough (1100-1200rpms) to make up for the greater throttle play, or something like a 3.73 rear so no throttle movement would be needed cruising at 60mph.

    Chevy could easily get a 26-27 highway mpg rating in their base model shortbed trucks if they offered a belt driven supercharged/intercooled v6 with a 3.23 rear and a 6 speed manual (with double overdrive). But they will never spend the money to do this.
  • mike537mike537 Posts: 4
    edited November 2010
    actually the turbo efficiency idea is not that it makes more power ]to move the truck easier. This is because when you see the highest mileage with the turbo you're not going to be under boost. What makes it more efficient is the slightly greater volume of air coming in at lower rpms vs. stock. This leans out the air/fuel mixture (which is usually corrected for in the tune), and the higher volume of air is what allows for a turbo engine to create a more dense air/fuel charge.

    for example if your car got 20 mpg, you add a turbo and no intercooler, you would be lucky to see 15mpg. So you can see it isn't the turbo or the extra power, it's simply the extra air coming in while under vacuum (not boost). What you do with that air in terms of cooling and tuning is what generates the extra efficiency.
  • mike537mike537 Posts: 4
    edited November 2010
    hutch, your 4x4 suburban does not get 24 mpg on the highway.

    The best mileaged 4x4 suburban is the new 5.3L 4x4 with 3.08's and the double overdrive, on the highway it gets 21mpg, 22 is great driving, 23 is stretching the truth but perhaps possible, 24 is [non-permissible content removed]. The 2wd tahoe hybrids don't get much more than 22 hwy. Fullsize 2wd pickups with the 5.3 and 6speed get at best 22mpg. S10 4.3L's with the same 3.08's get 26mpg at best. you are full of [non-permissible content removed].
  • I also agree there is no way you can get 23-24 mpg with a 4x4 suburban!!
    I also don't think your brother gets 12 mpg with his 1/2 ton ford unless he runs the nuts off of it, seeing as mine gets 18 mpg!
  • well i have a 07 chevy silverado, crew cab with the 5.3, im getting 12-13 mpg, i actully just took it to the dealer today and they say its fine ugh how do u get better mpg out of these trucks, this is rediculas!!!
  • nargnarg Posts: 113
    Hi all, I'm trading in a 2000 Silverado Ext Cab with the older 5.3L V8 that would easily get 21 to 22 MPG highway driving (though my wife got 24 MPG once or twice, no tailwind either!) for a new 2011 Silverado 5.3L Crew Cab.

    I attribute most of the over 20 MPG rating to a hard bed cover. It was a 4 piece folding cover that I loved. I plan to get the 3 piece cover that GM offers via the dealerships, but in a few months after I swallow the Tag/Title/Tax costs first.
  • Im having the same problem did you ever get it figured out?
    im only geting 11 mpg in town and 13-14 on highway. they say nothing is wrong.
  • My 2008 silverado used to get 18.5MPG HWY, and 13.5MPG city, but now I get 11.5MPG city, and 15.5MPG HWY. Took to dealer and they were no help, said could find no problems with truck, I think we got a big lemon! The only reason I bought this truck was because of the better MPG, I'll never buy a Chevy ever again unless this porblem can be fixed?
  • gmcustsvcgmcustsvc Posts: 4,001
    travelcheve,
    The best fuel economy possible is the direct result of proper maintenance and good driving habits. Listed below are GM's recommendations to achieve the best mileage possible. The first group are things to consider for your vehicle, while the second are tips relating to your driving habits.

    One of the major contributors to poor fuel economy are under inflated tires. Tires low with pressure create drag that the vehicle’s powertrain must overcome, wasting dollars in fuel. Always keep your tires inflated to the proper pressure as shown on the vehicle placard. This not only serves to increase gas mileage but cuts down on tire wear, further decreasing your costs per mile.

    A vehicle that has a dirty air filter can’t efficiently draw air into the engine. This restriction forces the engine to expend energy to "breathe" wasting fuel in the process. Change recommendations are found in your vehicle Owner’s Manual.

    Always use the proper viscosity oil in your engine. Oil that has a higher than required viscosity will create more drag on the internal components of the engine causing more work for it, especially when cold. Each Owner’s Manual contains information on the proper type of oil for your vehicle. Look for the "starburst" symbol on the front of the bottle, and the SM rating on the API circle on the back label. If you are in doubt, stop by your dealer for an oil change, and any other services required. Most current GM vehicles are equipped with oil life monitors to further assist on the "when" to change your oil. (Aveo/Wave/Optra/Epica currently do not have oil life monitors).

    Note: GM Vehicles DO NOT require additional engine oil additives. Some additives may cause harmful effects to the internal seals and additionally void the terms of your vehicles New Car Warranty.
    Purchasing higher than required octane fuel is a waste of money. Using higher octane fuels in a vehicle that only required regular unleaded fuel will neither increase performance nor improve gas mileage. In all cases refer to your owner’s manual and ONLY use the octane rated fuel recommended for your vehicle.

    Even though current GM vehicles have 100,000 mi (160,000 km) service intervals for spark plugs if your vehicle is at that point in its life, have the spark plugs changed to assure proper running and continued efficient, trouble free operation.

    Avoid quick/full throttle acceleration from a standstill in town and high cruising speeds on the interstates. While the optimum MPG for highway cruising speed varies from vehicle to vehicle, faster is almost always worse. If your vehicle is equipped with a Driver Information Center that displays Instant Fuel Economy, select that readout and vary your cruising speed while on the highway. The display will change continuously with uphill and downhill sections but you should quickly be able to identify on level ground the speed range that your vehicle does the best in. Avoid leaving unnecessary items in your trunk. It takes power to move increased weight and that means more gasoline consumption and reduced performance. While the change may be slight, multiplied by thousands of miles, it all adds up. Your vehicle uses much more fuel when the engine is cold. This is especially true in the winter months when the engine will take the longest to warm up. Combine errands or trips so that the vehicle only needs to warm up once to encompass many different stops.
    Please also feel free to get a second opinion from a different dealer.
    Christina
    GM Customer Service
  • gmcustsvcgmcustsvc Posts: 4,001
    aaroncorpus,
    I would recommend having your vehicle looked at by an authorized GM Dealer. I would also recommend reading post #132, as there are some helpful tips. Please keep me updated as to what the dealer says.
    Christina
    GM Customer Service
  • nibsnibs Posts: 65
    I’ve own a lot of trucks over the years. Until recently the last one was more than a dozen years ago. I got fed up with the drive quality, the fuel economy etc. Recently purchased a GM Sierra SLT, absolutely fully loaded. It does have the latest in electronic technology such as phone (bluetooth), Sat radio etc but GM has done nothing to address the fuel economy. My Sierra has the all aluminum engine, 6 speed transmission, active fuel management (YAWN) and a list a mile long of features but really, it means nothing if the GD truck farts gas by the gallon. I recently did a round trip of about four thousand miles and averaged 14.7 mpg. Granted I had an ATV in the dump but my speed was consistent at 55-60 mph. Around town with nothing in the dump, I get about 12 mpg. I guess in 12 years nothing but the shiny stuff has really changed with GM or the other domestics. I realize now why I gave up trucks all those years ago and went offshore. It is cheaper to rent one if you need it and have a quality buildt foreign with a tow hitch. The trailers today are mostly all aluminum and are light, so tow capacity is not so much an issue anymore. Anyone want to buy a truck? :lemon:

    Who combines errands to save gas? Vehicles are meant to be driven and in the years since my last truck, I’ve not had to consider fuel economy. My point being, GM has done nothing to address the problem as the same directions were given to people years ago by GM to reduce gas consumption. We should be given a gas rebate every year by GM IMO. That or put a light weight diesel under the hood for those of us who’ve spent $50k on a new truck. Good luck to you all.
  • duff333duff333 Posts: 41
    Just did my 1st tankful of 23 gallons and averaged 17.0 mpg. A mix of highway (going to work) and some 2 mile runs to the store etc. Overrall, I'm "OK" with the results but certainly would hope for closer to 19 on average over time.

    I've managed to meet or exceed the posted EPA mileage numbers on my last 5 vehicles. It does take some conscious effort to do that - -drive smooth and not too fast - - but can be done. Will see if I can improve on the 17 over time.
  • nibsnibs Posts: 65
    Recent highway trip. 1200 KMs. No towing, nothing aboard but me. Average speed on cruise 120 KPH. MPG = 16.68. Given technology today, I’m very disappointed.
  • barnowl3barnowl3 Posts: 70
    Christina,
    You reference air filter changes. My 03 GMC manual says to use the air filter monitor and does NOT specify the interval. Typically after 3 years and about 25,000 miles, the air filter monitor still indicates a very good filter, but I just change the filter. So, do I trust the GM monitor or do you recommend a minimum change frequency for the air filter?

    BTW my 03 Sierra 2500 HD has always gotten 10-14 MPG and 14 is tough to achieve. It is a 2500HD, 6.0L and has the higher numerical gear ratio, so that doesn't help. My 01 was slightly better as it had a slightly better gear ratio, so I assume this is normal for the 2500 GM gas trucks.
  • Quote: Recent highway trip. 1200 KMs. No towing, nothing aboard but me. Average speed on cruise 120 KPH. MPG = 16.68. Given technology today, I’m very disappointed.

    Are you kidding? You're cruising along at 120 kph (72 mph) and complaining about 16.66 mpg? I'd say you're doing very well.

    Keep your foot out of it and slow down if you want better mileage.

    Regards, Paul.
  • mrmagoo157mrmagoo157 Posts: 1
    edited April 2011
    Let me start by saying that I was searching for GM truck mileage improvements and found my way here. I have been a GM guy all of my life but have been severely disappointed with my '07 (45k miles) GMC crew cab, 5.3 w/AFM, 4x4 truck's mileage & problems. The sticker said 14/20 mpg and that was probably in some engineer's better dreams. The absolute best ever checked longhand and not trusting the calculator was 18.6 mpg going down hill on a trip at exactly 60 mph all the way. Any additional throttle would kick in the V8 mode so the AFM is truly worthless for highway cruising. The truck has averaged 13.7 mpg over its life and that is unacceptable since I drive a mixture of city/hwy. I knew this truck was made on Monday morning from day one when the valve train rattled on startup. I also discovered today that the rear ring and pinion gears have extreme play, the leaf springs squeak like a '50 Studebaker, etc, etc. I am considering a trade to something else SOON.....MrM

    BTW - Cruising at exactly 2 mph over the speed limit of most interstates is not exactly hauling [non-permissible content removed] or anything and considering we bought these trucks expecting 20 mpg + or - an mpg or so.........you get my point.
  • Mine is a 2010 Sierra Extended with 5.3. I and getting at least 17 mpg and up to 21.5. Now that is Imperial gallon, not US. Ours is a tad bigger.

    When I was researching trucks by driving Fords (originally my first choice) and GMCs, I took along my trusty ScanGuage II and plugged it into the computer plug so I could monitor the mileage properly. I dismissed a 2009 5.4 Ford because I had to really nurse it to get 16 mpg. I easily got over 19 with the 2010 Sierra, which I ended up purchasing. So far I am pleased.

    I hope you can resolve the lousy mileage you are getting.

    I am not certain that a Scanguage is required these days, cuz many vehicles tell you what the instantaneous and average mpg is.

    It would be interesting if you could drive a truck of the same year, engine, etc. and see if you get better results.

    Good luck.
  • erybilerybil Posts: 1
    I have a 2007 Silverado 4/4, 5.3 L. I bought this truck over both the Dodge Ram and the Toyota Tundra because of the gas mileage - 14 city, 19 highway, 16 combined. After tracking several tanks recently, I'm actually getting closer to 11.8 combined. My tires are properly inflated, my air filter is new, I don't do jack-rabbit starts. Very frustrating - if I thought there was a market for this truck right now (with gas prices being well over $4) I'd sell it and buy any of the other truck - both my previous Dodge Ram 4x4 and the Tundra I test drove before buying the Silverado handled like a sports car in terms of turning radius compared to the Silverado, and had I known I'd not get near the mileage claimed, I'd have bought the Tundra (as the 2007 Rams had a beast-like Hemi that was a gas-sucker even on their sticker).
  • inhaliburtoninhaliburton Posts: 4
    edited May 2011
    I wonder if there is any upgrade for the on-board computer that would improve gas mileage?

    My driving is exclusively on highways. If I was doing city driving my average might dive to 11 mpg cuz you're on the accelerator all the time. Looking at the instantaneous gas gauge, just touching the accelerator drops it below 10 mpg.

    Ford's done a marvelous job with their new engines mpg-wise. It makes me wonder why they didn't do it 5 years ago. It just shows to go you.

    Btw, I'm happy to see that Chryco is doing well by making some money! They are working hard and cranking out some good products these days.
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