Fuel Mileage

[sunstrand]

2009 gmc sierra 4x4 4.8 v8 4 speed automatic 15 miles to gallon since new any suggestion how to improve it no luck with dealer

[jhm]

2009 gmc sierra 4x4 4.8 v8 4 speed automatic 15 miles to gallon since new any suggestion how to improve it no luck with dealer

what kind of driving do you do, mostly non highway I bet. 15mpg is normal for non highway with a 4.8l if you are doing mostly highway you should be getting around 18. 4.8 is a great engine, i agree with redvett comments.

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Oh, you're a newbie, leave us all alone, go away! jk But why would you buy the 4.8l in the first place, it's kinda low on power and doesn't get great gas mileage because it has to try too hard to move itself. You should be getting more than 15, though. If I were you I'd tune it, and put an exhaust on it, and probably a cai as it compliments the exhaust so well. The tune should come first, that 4.8l will rev quick, and that's where its power comes from(what it does have).

[redvett]

Just get a custom tune and forget the CAI and exhaust that will cost more money than you will ever get in return.