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Mileage... 4500 mile road trip


Full Member
May 15, 2007
Baton Rouge, LA
2007 LT3,? 5.3 engine, 2-wheel drive...

Baton Rouge, LA to northern Arizona and southern Utah and back. (Grand Canyon, Lake Powell, Bryce Canyon)? When we got there, we had averaged 19.2 MPG driving 1600 miles (mostly interstate) at 70-75 mph. Then after driving approximately 1300 miles on mostly rural non-interstate roads at 50-65 MPH, the average got up to 19.6 mpg. Then after driving home on mostly interstate again, the final average for the 4525 mile trip was 19.42 mpg... 233 gallons of regular gas.

Not too bad for a big, heavy truck!
I checked after the trip to the National GTG and averaged about 17.5 to 18mpg overall after traveling 2600 miles at speeds between 75-80MPH interstate and very hilly driving in SD :B:
I haven't taken that long a trip in the AV but going to Branson Mo. next month so will watch my MPG. Thanks for the info.
I do drive from North Texas to South Texas, about 450 miles or so, about once a month and average 18.6 to sometimes 21. And thats at 75-80 MPH
I got my 2007 Avalanche (LTZ) a year ago and it has 23,000 on it.  My average mileage is 15.9 MPG.  Driving is half highway and half city.

I had a 2004 Avalanche (Z66) it had 68,000 mile on it when I tarded it in.  Same type of driving as my present 20007.  Average MPG was 16.
% highway / city? -- thanks, very useful info to me. Trying to figure out what it will really cost me in delta operating cost for the luxury(?) of driving a "comfortably" powered vehicle day-to-day at 6000 ft.
i'm in the same boat as twmac! i just drove 1300 miles from NC to upstate NY and back this weekend and i averaged about 13 mpg at about 80mph on cruise control... i thought that might be a little low... i even took the 22s off the truck and put the stock 17 back on. just had it serviced too!
Hate to hear about the low milage you all are getting.
Got back from Branson, Mo. My LT did great on fuel.  I have a 5.3 engine and averaged 18 mpg most of the time but when not real hilly, got 20 mpg. And again, that was at 75/80 mph.  FYI
I have 14K on it now and my average is 12.2mpg. It was 11.6mpg until recently, I took a 2k trip averaging 16.5mpg which brought it up to 12.2mpg. I know I drive kind of fast, but could there be something wrong with my particular AV?
Too bad to hear about the low mpg (n)

For those with this issue, I'd go to the dealer first, and if they can't find anything, I'd spend the $$ to have it dyno'd, and possibly tuned. I bought a Diablo Predator tuner for my '07, and when I had it on the dyno, the a/f % ratio was all over the place. The tune not only removed the governor, but stabilized the a/f % ratio, and added a little giddyup to boot. I drive around 100 miles per day in my commute, in both city and highway conditions, and I avg. right on 17mpg using 87 octane. For those interested, the Predator model used in the '07 5.3L V8 is U7194.

Good Luck,

Thanks for the input. I'll try talking to the dealer first.
I'm running 15.6 average driving.. haven't been pulling trailers though
the Mrs only averages 12.2 Total city driving