Any tips for better mpg

Smooth and easy on the pedals is the most efficient and cheapest method. Preventive maintenance and tire pressure are equally important. Don’t waste your money on gimmicky stuff, you’ll usually hurt performance and mileage. Also, make sure your wheels are perfectly aligned as well

being we have an 03 denali also, as many said keeping up on things is number one, tire type and size can make quite a bit of difference, as well as where your driving and probably the biggest is the how your driving it.

we get 12-14 on average with ours, but we don't baby it and have 285 druatracs on it ( I got 1-1.5 mpg swapping to snow tires on my avalanche) many of the items you are going to buy or pay for aside from upkeep will take a long time to pay for themselves, let alone save money.


using higher that needed fuel required will also do little to save money, as the little you could save will most likely be negated in the cost of the more expensive fuel.

being we have an 03 denali also, as many said keeping up on things is number one, tire type and size can make quite a bit of difference, as well as where your driving and probably the biggest is the how your driving it.

we get 12-14 on average with ours, but we don't baby it and have 285 druatracs on it ( I got 1-1.5 mpg swapping to snow tires on my avalanche) many of the items you are going to buy or pay for aside from upkeep will take a long time to pay for themselves, let alone save money.

in my experience even the 5.3 like my avalanche and Tahoe only get about 1 mpg better average driving, and the 8.1 about 1-2 less. for about 5mpg across all the trucks, but with them all being close to 6,000lb bricks in the wind, none are going to stellar.

Make sure air filter is clean/new, tires are inflated, and fresh fluids

Aviation gas (145) is a very pure fuel. There are literally no additives to the fuel other than the purple dye that is put in to identify leaks in the tanks & fuel lines. The recip engines are usually air cooled and the pistons are horizontally opposed so every stroke is basically a full power stroke, compression, intake or exhaust. BMW motorcycles use this set up and they kick butt. Instant power the moment you hit the throttle. The bikes have similar, yet smaller, heat syncs like the recips do.

I've never really noticed an increase in my engine temp (analog gauge) with the 93 as the difference in octane level is not that big of a difference, but I like to think every little bit helps. And as my A&P instructor stressed, "Burning hotter is a complete burn and that helps the engine stay clean". No deposits from unburned fuel or it's additives, no clogging valves or lifters. I have noticed that I get 17.1 MPG with 93 and around 15 with regular or 87.

As to my friends 68 Torino I believe he was running straight water as a coolant, which you could do with the old Ford 289s & 302s. Which was popular back then. If you were doing day to day driving water will do for a while, but over time the corrosion that builds up are crippling to an engine at that time. But one big disadvantage to water is it evaporates rather quickly, especially when the engine is being put to the test. Like when drag racing. (Oh, and I failed to mention that this event happened in the summer of 1981.)

Nowadays, coolants have so many additives that prevent corrosion, aid in lubrication of pump, pump bearings & keeps gaskets supple to prevent cracking. In short, you really can't just run water in newer/modern vehicles because the engine is designed to remain cool with a certain amount of proper coolant, not just water. You might use water to get it to a service center, but to just run water is a quick trip to engine problems.

All good suggestions above.

I gotta tell you, IMO, the mileage that you are currently experiencing is not bad at all for that truck. The Denali, with its large motor, was not designed for great gas mileage, but rather for performance, whether it be for quick starts or for towing. Depending on what I'm doing, I can get below 10 mpg when I'm out by myself just horsing around, or close to 18 mpg when my wife is in the truck, who has zero tolerance for horsing around.

Your best option for increased mileage, as already stated above, is to adjust your driving (gas pedal usage) habits. That is hard, though, as it is really fun to push the Denali and its motor.

You could also opt for a Black Bear Performance tune, which could be built to focus on better gas mileage (versus performance), and the folks @BlackBearPerf could estimate for you, just how much better gas mileage is realistically possible with one of their tunes for your Denali. It would cost you somewhere in the neighborhood of $600 to get a tune, though.

Another thing to consider is the LQ4s in the Denalis are pretty low compression at 9.4-1 that doesn't help efficiency or mpg. I agree with the people above that say your current numbers aren't bad for what you have.

On a known drive learn where you can let off the gas and coast to a stop sign or turn. I have four of such opportunities in my mixed drive. I usually pick up a few tenths doing this.

But then I blow it by romping through the gears with the paddle shifter so whatever.

PNWTahoe said:

The only way to get significant MPG increase is to buy a Chevy Metro and paint Denali SM on the side of it.

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I replaced my factory exhaust with Cat back 3" Flow Master 40 series cause that is the sound I like and I have averaged a +.8-1.0 mpg improvement as long as I keep my foot out of the gas other than that it is really the only improvement I have noticed. that gets me to right around 16.0 mpg on 200k 4wd Tahoe with 5.3L