Terrible fuel mileage

[Seamus]

These rigs are heavy. It doesn't take much to affect the mileage in a negative way. When I first bought my 2013 Suburban it was mechanically pretty well taken care of but was due for a lot of service due to mileage. It had 94K. I did a lot in the first month and gained about 2 mpg. I couldn't get over 17.2 on the highway. Yesterday I got 19.0 at 78 mph 250 mile round trip. 14 mpg in town is usual now.
My list of maintenance :

Wix air filter
Wix oil filter
Mobile 1 0/40W
4- O2 sensors
all new tensioners
new serp belt
iridium spark plugs
AC Delco wires
Amsoil sever gear synthetic rear diff fluid
Valvoline synthetic dex VI fluid
Wix trans filter and gasket
New Michelin Defender tires, 33 psi
cleaned throttle body
cleaned maf
Fuel injection cleaning
Alignment


Probably a few other things I forgot, but I would also check your hubs and calipers as they can drag and cause issues too. I have in the past put aftermarket rims on my Duramax and lost 4 mpg!! They were very heavy. Lightweight tires and rims can gain a lot mileage.

 

[petethepug]

Your milage is spot on for city. To alleviate some of the pain of an AWD vehicle’s in town milage, scroll through the settings on the cluster to bring up your MPG while driving on the highway. Press and hold down the checkmark button to reset your mileage while the vehicle is in motion.

You’ll see that your 6.2L w/ overdrive and 6SP auto does a hell of a lot better when out of town. The early NNBS trucks don’t have the clusters with the instant MPG feature, only the average MPG. I use the GasBuddy app on my phone to hunt down the best price on fuel. Wifey and I plan our errands around our 08 Denali XL fuel level.

Tomorrow we’re away from home so the truck is near a Costco that competes with a Sam’s Club on fuel prices. Here in SoCal that means $4.19 a gal on 91 vs $3.85 20 miles away. With a 30 gal fill up it cuts $16 off the fill up cost plus another $4 if we use a Costco Visa to pay.




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[swathdiver]

I have a 07 Yukon Denali and I’m only getting 11.5-12 mpg city driving. Wondering if that’s normal or if I should be looking into something

Could be normal depending on what "city driving" actually is. If you can't drive a mile without hitting a light, then that's pretty good compared with mine in stop and go!

 

[petethepug]

We have a lotta hills. Some are steep enough to get air on the up or down side of the road. Forgot to mention I have a lot of idle time if I have the truck on the days I p/u the girls from school. So my normal city MPG may be skewed a bit.


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[TahoeFL2017]

Idling kills my mpg.