2007 chevy silverado diesel poor mpg

Why does my Chevy silverado diesel truck have such lousy mileage? Brand new I got 15.8 and now all I get is 14.9 max. Occasionally I haul a light (3000lb) travel trailer. I buy the lowest (!) price diesel fuel. Is that the problem, or my leadfoot, or the turbo or the exhaust or a hole in the gas tank?


Not familiar with this truck, but many problems with mpg are due to driving habits. Don’t forget you are hauling around a lot of weight.

you can get milage increases as much as 40% by careful driving and proper car maintenance.

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changed your air breather filter lately?


Are you using the Tow Haul mode when pulling the trailer? That makes for a drop in mpg.

What truck model, engine size (6.6L?) and mileage?

Were you towing the TT when you got 15.8 mpg? I think not. Empty with no TT?, quite likely.

What method did you use to calculate fuel mileage and also, what did you take into consideration before calculating? (city/highway/hills/wind, truck bed loads, etc)

Hmmmm. 3000# isn’t exactly a light trailer and a 1 mpg loss depending on temperature, terrain, wind conditions, and so on isn’t a big drop. Make sure the timing is set correctly from a diesel shop. Mine never did run well until the timing was set and not according to the marks on the pump like the book said.

I buy the lowest (!) price diesel fuel. Is that the problem,


or my leadfoot,


or the turbo

Not if it is OEM, unless it is encouraging your lead foot.

or the exhaust

What is wrong with the exhaust? Not likely.

or a hole in the gas tank?

No, you have a diesel tank.

Installed a K&N air filter yesterday.

I was wondering about the settings. It sounds as if it running a little fast, but of course the dealer(!) treats me like an idiot. I only go there to get the TPM reset and had them do the first service.
I will check out the diesel shops locally.

I do use the tow mode ,but will experiment. That is not my main complaint tho’. I see no improvement in mpg while driving empty.
Truck is 2500HD 6.6 diesel, mileage is approx 23k.
I got 15.8 with the very first tank of diesel, when I picked it up at the dealership. Never again.
I caluclate mpg using the readout on the dash. It gives me the average but I also calculated the total mileage and total gallons used. I srive mostly highway, but also I live in the country and drive backroads. I would have thought 400 miles of non-stop highway would improve the mpg, but NOT!