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You should be seeing 16 to 18 MPG
I carry 1,000 pounds of extra weight in my Ram & i get 17.4 MPG on the highway, running Summer Blend gas. I still have Winter Blend gas in it right now & i am getting 15.8 mpg.
The only things that i have done to it were a spark plug change & a throttle body cleaning at 42,000 miles, i now have 63,000 miles on my '09 fully loaded SLT Quad Cab
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