MPG disapointed ??

[mabr]

Just curious what you folks think on this. 2011 Silverado, 6k miles on it now. Engine is 5.3 with active fuel management , rear end is 3:43. 18 inch tires

Sticker says It should get between 15-21 mpg. I’ve reset the computer a couple times to check and see if there are any differences in how I drive it. I’ve also checked it manually with pen and paper. Both are correct within an amount that is negligible. It averages 12-13mpg for every day driving (city and highway). Highway it was 16.2, that’s running on 94 for 2 hours from Alexandria to my home at speed limit of 70 with cruise control on.

Does this seam right? I happened to fill up next to an identical truck as mine last week and asked the guy what he got for mpg. Off the top of his head said 18-20. I asked if he drove pretty mild or got on it. He said he didn’t baby it at all and was more aggressive. So I asked him if he would look at what the computer said he was getting. It said 17 as an average. Now from what he told me he drives into the cities every day and that’s a combined average.

Now I know it’s a truck we don’t expect great mileage but 5 mpg difference between that truck and mine is a lot IMO. I’ve started driving a lot less aggressive to see if it mattered and it really hasn’t. Some may remember I posted my MPG after pulling my boat to Texas as 12 mpg averaging 65 mph which was great. But why would it stay in that mpg range with every day driving? Could the rear end ratio be the difference? I like the truck so don’t get me wrong but I’m about to ask GM if anything can be done.

[Capt. H (Ret.)]

I bought a brand new 2011 Chevrolet set up the same way yours is and at first I wasn't real impressed. About the time the truck had about 8,000 miles on it I noticed a significant increase in fuel mileage. I burn regular 87 octane fuel and don't use the ethanol. I filled up tonight at FF and averaged 19.2 mpg for city and highway driving. NOT BAD IN MY BOOK!!! I really think the more miles you get on the truck the better the mileage will be. Hang in there.

Capt. H

[Big_Sandy_Lake]

Check tire pressure and air filter as well.

[brian6715]

That thing isn't even close to broken in yet. You will not see your peak mileage until 15,000+. I wouldn't worry about it at all. My buddy bought a Dodge Diesel and he was first getting 8mpg, it didn't peak until 17,000 when he was getting 20+ mpg.

[Dave S]

Are you running unleaded or E-85? Your MPG sounds like E-85 mileage.

[K_Josh87]

gotta love the practicle thinkers... seams like a very logical question

[Dave S]

gotta love the practicle thinkers... seams like a very logical question

I only brought this up since I witnessed a person reaming a service managers arse because his new Silverado was only getting 15 mpg on the highway. I stepped in and asked what fuel he was running and sure enough.....E85. Problem solved.

[Dave S]

In addition to my previous post, E85 has a higher flash point so it takes more fuel to achieve the same BTU rating as regular unleaded fuel.

[delcecchi]

It takes more fuel because ethanol which is the 85 in E85 has inherently less energy content when burned than gasoline does.

[mabr]

Are you running unleaded or E-85? Your MPG sounds like E-85 mileage.

Unleaded only have even tried the higher octane stuff. I just dont get the break in period. Ive never heard of a gasoline motor needing break in besides the valves seating, diesel yes but not a gas.

[MJ1657]

I don't think it necessarily has to with just the engine. The whole vehicle just needs to loosen up a little bit.

We had this same comcern constantly at the dealership. Told people to put some miles on the vehicle and let us know what happens. Mileage almost always went up after awhile.

[SkunkedAgain]

I just dont get the break in period. Ive never heard of a gasoline motor needing break in besides the valves seating, diesel yes but not a gas.

There is a difference between a break-in period like you used to have on older cars, and vehicles slowly working towards peak MPG. There are lots of little engine imperfections and otherwise that get breakdown overtime allowing the engine to work more efficiently.

[SkunkedAgain]

There are lots of little engine imperfections and otherwise that get breakdown overtime allowing the engine to work more efficiently.

I don't know what I was smoking yesterday, but that should have read:

There are lots of little engine imperfections that get worn down over time allowing the engine to work more efficiently.