Hello im new to the forum. I have a 09 GMC Sierra with 40k miles with the 4.8 vortec and its 2WD with the super cab and 4 spd tranny. I was told the truck should get around 18-19 MPG hwy and the comp on the truck is saying around 16 the truck has descent power but figured it would be a little better with smaller displacement. Any suggestions on improving fuel economy is there a recall on this particular year? Just curious if im doing something wrong or is there something I can do to help this truck get better MPG. Any feedback is much appreciated.
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GMC Sierra Gas Mileage question
- Thread starter Todom
- Start date
paultbear
New member
yep.... depending on your driving patterns, a smaller engine may not be more efficient for fuel usage. It may be that it runs outside of the most efficient rpm range when producing the power it requires. This is more noticeable when loaded or towing, or if you are aggressive in your driving.
You are not the first I have seen complain about gas mileage with a small V8 and a 2 wheel drive truck.
Fuel mileage is a very tricky thing. You can take 2 people with indentical vehicles and the mileage they get can vary widely due to personal driving habits. There are many variables that affect mileage such as: tire inflation, the wrong size tires, the wrong type of tires, the type of fuel, weather, elevation, the speed at which you drive, the gear in which you drive, the speed with which you accelerate, engine maintenance, excessive idling, cruise control, the grade of motor oil you use, stuff you haul around, accessories you add to the exterior that impacts aerodynamics and so on.
My truck has averaged 17.7 mpg over 20,000 miles. High has been near 20 and low about 15 in winter months using AUTO 4x4 regularly. The only thing I have done to my truck was to install synthetic lubricants everywhere and I know with my AWD CTS4 that accounted for an increase of +0.2mpg.
Also note, fuel is a big factor. Its not a myth but its 100% true that ethanol fuels get worse mileage. So if any of the fuel you are using has ethanol in it, that can account for a lower mpg. Those in favor of those fuels refuse to accept that as truth but its a fact.
2010 Sierra SLT Ext Cab Z71 All Terrain 5.3L
2009 CTS4 Performance Sedan 3.6L
Fuel mileage is a very tricky thing. You can take 2 people with indentical vehicles and the mileage they get can vary widely due to personal driving habits. There are many variables that affect mileage such as: tire inflation, the wrong size tires, the wrong type of tires, the type of fuel, weather, elevation, the speed at which you drive, the gear in which you drive, the speed with which you accelerate, engine maintenance, excessive idling, cruise control, the grade of motor oil you use, stuff you haul around, accessories you add to the exterior that impacts aerodynamics and so on.
My truck has averaged 17.7 mpg over 20,000 miles. High has been near 20 and low about 15 in winter months using AUTO 4x4 regularly. The only thing I have done to my truck was to install synthetic lubricants everywhere and I know with my AWD CTS4 that accounted for an increase of +0.2mpg.
Also note, fuel is a big factor. Its not a myth but its 100% true that ethanol fuels get worse mileage. So if any of the fuel you are using has ethanol in it, that can account for a lower mpg. Those in favor of those fuels refuse to accept that as truth but its a fact.
2010 Sierra SLT Ext Cab Z71 All Terrain 5.3L
2009 CTS4 Performance Sedan 3.6L
nikolaiak2007
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Part of the gas mileage issue is right there in what you wrote: the small 8 with the 4 speed. While it's true, the small 8 does better mileage wise, the 4 speed counters it. the gear ratio with the 4 speed makes the engine run at a higher rpm. I had a friend of min with the 4.8 (I run the 5.3 in my truck), and I found that when it comes to the city, he beats me by anywhere from 3-5 mpg. when the highway kicks in, however, I even out (before the 4 cyc. kicks in)
I fully agree with Z15, with respect to driving habits and the fuel. I am a HUGE believer in routine maintenance.
It seem that the newer 4.8's don't get the same mileage as older models. Looking at the stickers, on newer trucks, the mpg's are lower than my 2000. Having bought my 2000, with a 4.8, I can still get 18 mpg on the highway, which is only 2 mpg difference from when I bought it. I currently have 351,000 miles and couldn't be happier. Good luck
It seem that the newer 4.8's don't get the same mileage as older models. Looking at the stickers, on newer trucks, the mpg's are lower than my 2000. Having bought my 2000, with a 4.8, I can still get 18 mpg on the highway, which is only 2 mpg difference from when I bought it. I currently have 351,000 miles and couldn't be happier. Good luck