Gas Mileage on trip.

[swathdiver]

Wow you guys are getting low fuel mileage. I get 19mpg at 78mph in my yukon Denali 6.2. I get 13mpg n city. I've manually estimated my mpg since I've owned the truck and have never been able to get more than that. Stock engine, no mods. Stock tire size. I do have replica snow flake wheels which are a tad bit lighter than the oem Denali wheels I took off. Didn't really make a difference.

That's fantastic! What brand and octane of fuel are you using and where do you live? My neck of the woods is flat so there's no coasting down hills. What type and brand of tire are you running?

 

[kbuskill]

Wow you guys are getting low fuel mileage. I get 19mpg at 78mph in my yukon Denali 6.2. I get 13mpg n city. I've manually estimated my mpg since I've owned the truck and have never been able to get more than that. Stock engine, no mods. Stock tire size. I do have replica snow flake wheels which are a tad bit lighter than the oem Denali wheels I took off. Didn't really make a difference.

More importantly... what rear end is in your truck... I'm guessing 3:42s or maybe 3:08s because your mileage is better than mine at highway speeds and worse around town and I have 3:73s.

 

[swathdiver]

Denalis come with 3.42 gears exclusively, pretty sure. I figure he has a K2 and not a GMT900 as well.

 

[Mrsteef]

The wife, kids, and I go to and from Orlando/Disney all the time and I used to average around 15.6mpg. Now that I had the fuel pump and fuel pump flow control module replaced I only get around 11-14mpg. This is pretty weird because I when I had my Silverado I’d average close to 16mpg on the same trip and if I were towing my drift car on the trailer it would be around 12mpg. Seems like ever since my pump and module were changed out in the Tahoe I seem to get worse mileage.

 

[swathdiver]

The wife, kids, and I go to and from Orlando/Disney all the time and I used to average around 15.6mpg. Now that I had the fuel pump and fuel pump flow control module replaced I only get around 11-14mpg. This is pretty weird because I when I had my Silverado I’d average close to 16mpg on the same trip and if I were towing my drift car on the trailer it would be around 12mpg. Seems like ever since my pump and module were changed out in the Tahoe I seem to get worse mileage.

Is it possible they used the wrong parts? '09s like yours were rated for 14 city and 20 highway and 16 combined. At what speed did you get 15.6 mpg on the way to Mickey? Or was that an average for the trip?

 

[Mrsteef]

Is it possible they used the wrong parts? '09s like yours were rated for 14 city and 20 highway and 16 combined. At what speed did you get 15.6 mpg on the way to Mickey? Or was that an average for the trip?

That was with me driving around 80-85mph but averaged

 

[Mrsteef]

Think I may have found my issue and it’s my own fault lol. Tires were a bit under inflated. Bumped them up to 35-36psi and got this result between yesterday and today

 

[Warriorpluto]

More importantly... what rear end is in your truck... I'm guessing 3:42s or maybe 3:08s because your mileage is better than mine at highway speeds and worse around town and I have 3:73s.

I have 3.42

 

[swathdiver]

Think I may have found my issue and it’s my own fault lol. Tires were a bit under inflated. Bumped them up to 35-36psi and got this result between yesterday and today

That's good news Chris. What kind of tires and what size are you running?

My last tank of fuel averaged 13.2 mpg on E85. My truck has always seemed to get better mileage on E85 than gasoline, not that E85 will deliver higher numbers, just not too much lower than gasoline. I'll run another test on gasoline when the prices come down. I like paying $2.29 a gallon for racing fuel!

 

[Mrsteef]

That's good news Chris. What kind of tires and what size are you running?

My last tank of fuel averaged 13.2 mpg on E85. My truck has always seemed to get better mileage on E85 than gasoline, not that E85 will deliver higher numbers, just not too much lower than gasoline. I'll run another test on gasoline when the prices come down. I like paying $2.29 a gallon for racing fuel!

My truck will be about 2mpg less on e85. The truck is on the factory 20” wheels with 275/55/20 Hankook dynapro HT’s