New silverado 5.3 gas mileage question?

[Kody]

I've been looking at new silverados and see that some have 18 listed as highway mpg and some have 21? Thought the differences could be motor, gearing, flex fuel, active fuel management, transmission speed... but the more I compare the more they seem to be mostly be 5.3's, flex, afm, 3.42, 6 speeds? Is there something I'm missing?

[johnnyelohssa]

I noticed that too when I was shopping for my truck. I think the discrepancy is window stickers themselves.

 

You're not missing anything. If you go the GM website and look at the specs, You'll notice the 4.8 with the 4 speed is rated at 13 city and 18 highway. While the 5.3 with the 6 speed is rated at 15 city and 21 highway.

 

At least that is what I have gathered after 10 months of shopping for a new Silverado.

[426ted]

I would think that the fuel economy would vary depending on the options for the truck which effect the weight. Remember that these figures are gained under ideal/unrealistic conditions. Sure, you may acheive these numbers if you leave from a dead stop slower than your grandma, and if you never take you truck over 100kph (80 is ideal). I average 13.8mpg with 60/40 city/highway driving, and that's driving normal.

[foghorn23]

My 2011 5.3 AFM with 3.42 and 6 speed is rated 21 Highway. You'll find all kind of discussion about gas mileage on these boards for the 5.3. In my experience if it is driven for efficiency you can get close to 20 out of it (55 mph/easy acceleration/ etc) You can also drive it where it will get MUCH less. Mileage is better in the summer running on the summer gasoline blend.

 

Don't know about the new Ford engines; I do know the 3.5 ecoboost is rated higher, but GM has historically been the gas mileage leader for years in my opinion. Nevertheless, I personally have never gotten the 21 figure for any distance on the interstate.

[BlackZ71Silverado]

Window stickers have unrealistic MPG ratings, they are not done in the real world. No matter which truck you choose, do not expect to get the average mpg listed on your sticker. My 2010 actually gets better mpg with the afm turned off, why I don't know.

There are many variables to take into consideration for fuel miles. Load on the truck, wind, temperature, the way you drive. They need to start doing real world testing and not controlled in a lab somewhere to get real numbers.

[Daryl LBZ]

Window stickers have unrealistic MPG ratings, they are not done in the real world. No matter which truck you choose, do not expect to get the average mpg listed on your sticker. My 2010 actually gets better mpg with the afm turned off, why I don't know.

There are many variables to take into consideration for fuel miles. Load on the truck, wind, temperature, the way you drive. They need to start doing real world testing and not controlled in a lab somewhere to get real numbers.

 

 

 

 

So did my 2009. In my area theres so many slight hills and grades that the truck would just bog down and switch in and out of AFM Mode Constantly. With the AFM turned off the truck ran a lot smoother, and got better Mileage. AFM is not the greatest thing to have around here.

[MikeNH]

Don't take anything the window stickers say with any sort of seriousness. My 2011 is rated for 21 hwy and the best I can usually manage (even on total highway trips) is 17, maybe 18. This is the AFM 5.3 (though it rarely kicks in around here, too hilly), 6 speed and 3.42s.

[Kody]

I agree with what everyone is saying, but still confused why what seems to me to be identical trucks are showing two different mpgs?

[johnnyelohssa]

Kody, are you talking about the listings on the window stickers that are on the trucks themselves?

[NHSilverado]

Sometimes dealer websites list even the 5.3 at 13/18. All 5.3 should say 15/21 and 4.8 I believe is 13/18?

[fishbones182]

my truck is an 08 with 5.3 and 3.73 rear z71 and i get a solid 17 highway and around 12 city. How do i turn off the afm its a real bummer and i cant stand being able to feel it kick it and out.

[txab]

Turn AFM off with a tune

[Zembonez]

I think the difference is the 6 speed versus the 4 speed. Also - don't believe you are going to get rated mileage out of any full sized truck. I know we have those here who get miracle mileage, but most get about 16-18 max.

[mikeySP307]

The reason for the contradicting mileage figures is the difference between the 4.8L and the 5.3L. For most of these trucks (WT, LS, LT), the standard V8 is the 4.8L that gets 18hwy. The 5.3L is an aptional engine that gets 21hwy. According to the EPA figures, transmission and rear end choice don't affect hwy mpg (!!!!!).

[350camaro]

I have been getting between 16 and 18 in my truck with about 65% highway. After I got my truck a year ago, I checked out the EPA website and the impression I got from it was that their gas mileage tests are done running pure gas (ethanol free). If I remember correctly, I think there were about three vehicles in the list that were footnoted as being tested with e10 but they were not our trucks, this may be part of the reason for the lower than advertised mileage.