I have read all the feedback on good gas mileage in the gas milage threads. My problem is my 2011 GMC Sierra Extended cab. It has the 4.8L engine with a 6 spd trans. It came with the 6" lift Rocky ridge package and 35" tires. The truck now has 1100 miles on it. I took a 400 mile trip on monday and got 10.5 miles per gallon utilizing cruse control the entire way. I'm very disappointed because the truck I traded in got 16+ miles to the gallon on previous trips to the same location. I think there may be something wrong with the truck. Has anyone else had this same problem? At this point I'm sorry I got rid of my dodge with a hemi in it. I had more horse power and better milage.
Feedback for bad gas milage
- Thread starter jeepman
- Start date
The tires are a big part of the problem. They have a lot more rolling resistance
Big tires = poor fuel mileage
Big tires = higher gear ratio and engine operating out of its designed torque range which can rob hp
more weight = more effort from the drive train
A larger diameter tire also has a larger circumference and travels farther with each revolution. Your odometer is calibrated for a specific dia/circumference tire. The larger tire will throw your MPG computations off making it appear that you have traveled a shorter distance (based on the odometer reading /fewer revolutions) on a tank of gas.
You bought the truck because you liked the lift and big tires and now you are finding out the hard way, big tires suck.
Big tires = poor fuel mileage
Big tires = higher gear ratio and engine operating out of its designed torque range which can rob hp
more weight = more effort from the drive train
A larger diameter tire also has a larger circumference and travels farther with each revolution. Your odometer is calibrated for a specific dia/circumference tire. The larger tire will throw your MPG computations off making it appear that you have traveled a shorter distance (based on the odometer reading /fewer revolutions) on a tank of gas.
You bought the truck because you liked the lift and big tires and now you are finding out the hard way, big tires suck.
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I understand exactly what you are talking about. I have had large tires in the past and only lost 1 or 2 miles to the gallon. Not 8 miles to the gallon. The truck comes with it calibrated for the tires. The bottom line is if it only is going to get 10 miles to the gallon then they need to remove the sticker that says 18 miles to the gallon. This add on is a factory authorized add on not just a shade tree mechanics work. We will see what GM came up with when I pick the truck up later today.
The dealer might have added that equipment but its not GM approved.
IMO the 4.8L engine is underpowered for a lift and oversize tires like this.
Whats the gear ratio of the truck?
What rpm does the engine turn at 55mph in 6th gear? My 5.3L is about 1600 with 3.42 ratio.
Mike
2010 GMC Sierra SLT EXCAB SB Z71 All Terrain
2009 Cadillac CTS4 AWD Performance Sedan
IMO the 4.8L engine is underpowered for a lift and oversize tires like this.
Whats the gear ratio of the truck?
What rpm does the engine turn at 55mph in 6th gear? My 5.3L is about 1600 with 3.42 ratio.
Mike
2010 GMC Sierra SLT EXCAB SB Z71 All Terrain
2009 Cadillac CTS4 AWD Performance Sedan
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I'm not sure where you are getting your information on the lift package but here is what I'm being told by the person at the dealer who actually does the ordering. The dealer orders the truck from GM with the package on it. The truck goes directly from GM to Rocky Ridge to add the package once the truck is done then it goes to the dealer. The dealer has no communication with Rocky Ridge at all. The truck arrives at the dealer with a 100% factory warrantee from GM. Just curious where you got your information that it is a dealer thing and not authorized by GM???
The truck has 3.42 gears.
I'm not sure about the trucks RPM at 55 MPH. I will check it when I get it back.
I agree that the truck seems to be underpowered especially after having the dodge hemi in the truck I traded.
Hi jeepman,
*
Your first post says you have a 6 speed.* Are you sure you have 4.8 with a 6 speed?*
*
I thought the 4.8 guys were lucky and had the older, proven, 4 speed without the new six speed problems GM has been inundated with since 2009.
*
I’ve got the clumsy 5.3 tranny and was told by the GM salesman it would do better than the 4.8 due to the 6 speed (MYC 6L80).* Compared to my friends 4.8s, “IT DON’T”!
*
They beat me in MPGs and drivability.
*
GM appeared to be in a bit of a bind with the FEDs beginning in 2009 when they took the TARP money and said nothing when the FEDs raised/MANDATED increased CAFE standards.*
*
They took the $54 Billion and had to “match” mile per gallon mandates without complaint.* They just took billions from the folks that raised the MPG standards right?
*
Did your Dodge have 35s?* That has to have at least a marginal effect.
*
And don’t feel like you’re alone.* Many new GM truck owners miss their old trucks.* Doesn’t matter if it was an old GM, Ford or Dodge.
*
Your first post says you have a 6 speed.* Are you sure you have 4.8 with a 6 speed?*
*
I thought the 4.8 guys were lucky and had the older, proven, 4 speed without the new six speed problems GM has been inundated with since 2009.
*
I’ve got the clumsy 5.3 tranny and was told by the GM salesman it would do better than the 4.8 due to the 6 speed (MYC 6L80).* Compared to my friends 4.8s, “IT DON’T”!
*
They beat me in MPGs and drivability.
*
GM appeared to be in a bit of a bind with the FEDs beginning in 2009 when they took the TARP money and said nothing when the FEDs raised/MANDATED increased CAFE standards.*
*
They took the $54 Billion and had to “match” mile per gallon mandates without complaint.* They just took billions from the folks that raised the MPG standards right?
*
Did your Dodge have 35s?* That has to have at least a marginal effect.
*
And don’t feel like you’re alone.* Many new GM truck owners miss their old trucks.* Doesn’t matter if it was an old GM, Ford or Dodge.
Wartsnuff
New member
sorry to here that.. .my 2011 GMC 5.3L 6spd tranny got 28.8usmpg on the hwy
i think that totally acceptable
I think the 4.8l only comes with a 4spd and with the big wheel package and lift... you gas economy sounds correct
sorrygood luck
cheers
Warts
I was wrong I do have the 5.3. I spoke with service manager regarding my gas milage and it looks like there is nothing they can do about it until it has 5000 miles on the truck. He was very honest with me and said this is the worst he has seen out of these trucks with the exact same configuration. They put the truck on the scope and it showed nothing being wrong.
I pulled the window sticker out of my files and it indicates that the "expected range for most drivers 17 to 25 MPG highway 12 to 18 mpg city".
Very disapointed.
That's the truck without that conversion. GM did not install the lift and therefore has no control over it. You should have gotten another window sticker that details the upfitter package and the cost but they probably are not required to list mpg. For instance, a friend ordered a Sierra with a tool box in place of the box, he paid for the truck and another for the Monroe box conversion which the dealer ordered for him from Monroe and then added the ship-thur code from below to the order. GM does not warranty his box, Monroe Truck Equipment does.
here are the only ship-thru to codes I can find for upfitters
2011 GMC Sierra 1500 SEO OPTIONS/SHIP THRU CODES
Ship Thru Codes
A4I NEW! Ship Thru, Produced in Ft. Wayne Assembly and
shipped to Brand FX Body Company, IN and returned to Ft.
Wayne Assembly
(MSRP = $480.00)
1 - Not available on models **10543.
A1 A1 A1 -- A1
CJD Ship Thru, Produced in Ft. Wayne Assembly and shipped to
Reading Truck Equipment, Pontiac Michigan, and Returned
to Flint Assembly
(MSRP = $325.00) Requires models **1**03 or **1**53.
1 - Not available on models **10543.
A1 A1 A1 -- A1
TCM Ship Thru, Produced in Ft. Wayne Assembly and shipped to
Monroe Truck Equipment, Flint Michigan, and Returned to
Flint Assembly
(MSRP = $325.00)
1 - Requires models **1**03 or **1**53.
A1 A1 A1 -- A1
TRE Ship Thru, Produced in Ft. Wayne Assembly and shipped to
Ft. Wayne Fleet Equipment
(MSRP = $125.00) Requires models **109*3 or *K10753
1 - Not available on models **10543.
A1 A1 A1 -- A1
TW3 NEW! Ship Thru, Produced in Silao and shipped to Brand
FX, Ft. Worth, TX.
(MSRP = $445.00) Returned to Arlington Assembly for shipping
to final destination.
1 - Requires **10543 models only.
A1 A1 A1 A1 A1
VDE Ship Thru, Produced in Ft. Wayne Assembly and shipped to
Knapheide Truck Equipment
(MSRP = $325.00) Requires models **10**3
1 - Not available on models **10543.
A1 A1 A1 -- A1
VTT Ship Thru, Produced in Ft. Wayne Assembly and shipped to
Buckeye Truck Equipment
(MSRP = $300.00) Requires models **10703, **10903 or
**10753
1 - Not available on models **10543 or **10953.
A1 A1 A1 -- A1
VWB Ship Thru, Produced in Ft. Wayne Assembly and shipped to
W A Jones, Columbia City, IN
(MSRP = $200.00) Returned to Ft. Wayne Assembly for shipping
to final destination. Requires models T*10**3.
1 - Not available on models **10543.
A1 A1 A1 -- A1
VWH Ship Thru, Produced in Ft. Wayne Assembly and shipped to
Leggett and Platt/Masterack Truck Equipment
(MSRP = $340.00) Requires models **10**3
1 - Not available on models **10543.
A1 A1 A1 -- A1
2011 GMC Sierra 1500 SEO OPTIONS/SHIP THRU CODES
Published November 4, 2011 Page 94
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We are not talking about a monroe box conversion. We are talking about the dealer ordering a vehicle from GM with the convertion. GM sends the vehicle to Rocky ridge. The vehicle is then delivered to the dealer. The dealer has no communications with Rocky ridge. Thus GM backs it with the factory warantee. I realize some don't want to believe that. Call your local dealer and ask them to send a truck off there lot to Rocky Ridge. It won't happen. It must go through GM first. Now if the the guy that orders these truck from GM is lying to me please let me know. I took the man for his word. Just maybe he is full of crap and you are right. Please let me know.
Oh by the way I'm down to 8.7 MPG and the dealer states theie hands are tied by GM until it has 5000 miles on it.
I really should have known better than to purchase a GM product. I have been a dodge truck owner for many years with no problems like this. I spent 50K for this truck and I'm really not happy. The 5.3 is just so under powered. 1100 miles on it and I think I will just trade it in. Oh well live and learn.
I just got off the phone with GM regarding the Rocky Ridge package. They stated that my truck was sent directly from GM to Franklin Springs, GA to have the package installed they looked it up by the VIN number to verify that information. He stated that this package was not installed by the dealer. My window sticker also indicates the Rocky Ridge package. He also stated that the 17 to 25 miles per gallon is what should be expected with mine being toward to lower number 17 because of the larger tires. At least now I have heard it right from GM. He did indicate that a dealer can have this package added but most do not because they can do it when the order the truck and doing it themselves is not cost effective. So based on this information everyone is right. The dealer can do it or GM can do it. Mine was done by GM.
abfitch1212
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Terrible gas mileage
hello I am new to this site but saw your post about mpg with your sierra. I have a 2011 gmc sierra 1500 4x4 crew cab. I called gm at 5000 miles about the mpg. city I am getting 13.2 and highway was 16.0. They said take it to dealership so I did and said nothing was wrong. So gm called back and said they were sorry there was nothing we can do. Now I have 10500 miles just went on a 200 mile all highway trip. Going down got 16.5 and on way back got 17.3. Sticker says 15 city and 21 highway. Called gm again and took to dealership and again same outcome nothing. I am so fed up with mileage and there faulse advertisment on the sticker. I wish I never bought this truck. I was going off all the talk about this truck having the best mpg for there class. They are totally wrong. I was on phone yesterday with GM and all they can say is the dealership said there is nothing wrong. There probally is nothing wrong with the truck but when u tell people you should be getting 15-21 people are going to be pissed. I would say to everyone out there if u are unhappy with the mpg to call gm
tyler
hello I am new to this site but saw your post about mpg with your sierra. I have a 2011 gmc sierra 1500 4x4 crew cab. I called gm at 5000 miles about the mpg. city I am getting 13.2 and highway was 16.0. They said take it to dealership so I did and said nothing was wrong. So gm called back and said they were sorry there was nothing we can do. Now I have 10500 miles just went on a 200 mile all highway trip. Going down got 16.5 and on way back got 17.3. Sticker says 15 city and 21 highway. Called gm again and took to dealership and again same outcome nothing. I am so fed up with mileage and there faulse advertisment on the sticker. I wish I never bought this truck. I was going off all the talk about this truck having the best mpg for there class. They are totally wrong. I was on phone yesterday with GM and all they can say is the dealership said there is nothing wrong. There probally is nothing wrong with the truck but when u tell people you should be getting 15-21 people are going to be pissed. I would say to everyone out there if u are unhappy with the mpg to call gm
tyler
Although I certainly understand and don't necessarily disagree, I'd like to point out there isn't a manufacturer out there this doesn't occur, just read an article about some new ford hybrids rated on there stickers for 47 mpg, imagine the owners surprise when they actually got 10+ less in real world driving, my point is this our driving habits dictate in large what kind of mileage we ultimately get and most drivers are not going to get the optimal 21 these trucks are capable of. This isn't new in the new car industry and a little research online could have probably kept people from feeling ripped off if they really thought they were going to see 21,
When I purchased my truck just over a week ago 2013 gmc sierra w/ 5.3 liter imagine my surprise when I ran with the free fill up the dealer gave me and only got 250 miles on that tank, I traded a car that got almost 30 mpg and was getting 11 , what I discovered was dealer put e85 in to save a buck, my next fillup I was getting 17. If you want to maximize your mpg turn your DIC to instant fuel economy and modify your driving habits while watching that display, I did this and on a 30 mile trip I am getting 20.5 mpg in my truck. My .02 your mileage may very!
crazycat616
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be thankful for the milage you are getting.
I have a 2009 Serri 4X4 ext cab 5.3l 4spd auto and my milage is getting wourse by the day. I'm getting 400km on a full tank of gas I used to get 700km on the same tank. The deal saids there is nothing wrong with the truck because the computers come up no problems.I have an appointment with a small town garage and going to let him have a go at this problem.
As for the MPG they list on the stickers you have to remember that the get the results when they fine tune the truck and thay drive at 77 km on a flat surface with no wind or other car. They have to get the highest milage for the goverment or they get fined or shut down. do a search on how they get the mpg. GM used to have links on how they get the mpg but have not seen it since the standards have incereased.
Will post with the results of the small town garage findings and if the milage inproves with the changes he makes.
I have a 2009 Serri 4X4 ext cab 5.3l 4spd auto and my milage is getting wourse by the day. I'm getting 400km on a full tank of gas I used to get 700km on the same tank. The deal saids there is nothing wrong with the truck because the computers come up no problems.I have an appointment with a small town garage and going to let him have a go at this problem.
As for the MPG they list on the stickers you have to remember that the get the results when they fine tune the truck and thay drive at 77 km on a flat surface with no wind or other car. They have to get the highest milage for the goverment or they get fined or shut down. do a search on how they get the mpg. GM used to have links on how they get the mpg but have not seen it since the standards have incereased.
Will post with the results of the small town garage findings and if the milage inproves with the changes he makes.