2007 - 2008 5.3l Fuel Mileage

[dmjr77]

I was wondering what everyone getting for fuel mileage with there 07-08 5.3's?

[98 Z71 SLT]

Nothing impressive...

 

14 mpg city, maybe 16 mpg highway

 

Horrible fuel mileage, actually. This is an 08 Sierra Extended Cab, 3.73, 4x4 5.3

 

My 2006 Sierra blows away my 08 in the gas mileage category

 

the 06 with 310hp 5.3 nailed 17 city, 22 highway with ease...

[d3athsong]

Just added the DIC switch yesterday, so nothing had been zeroed out yet. It showed 18 MPG US as an average since new. It got worse then that when it was new, and know with a few miles on it, its getting just over 20 MPG US. That is mostly highway driving.

[slimjim2525]

I'm averaging 17mpg combined.

[hubbycap]

17 mixed, pure highway 21. 3.42, 13,800 miles

[Jake Wade]

16.2-17.1 mixed. 17.8 is the best ever all highway. BTW that hand calculated.

[vmaxx05stud]

up here in cold weather it drops alot as well. i havent got enough miles on mine yet to tell what its going to get. im hoping for around 18 mpg but its wishful thinking i'll bet.

[BigHerky]

12-13 around town and 17-19 on the highway with 3.42's and 265/70/17 tires

[BigJayDogg3]

Why is the 5.3 mileage so low? I get about that in my truck.

[iminaquagmire]

13 currently. Highest I saw was 15.5. However this is all city driving with a 3.42 rear end. If I had some some steeper gears I'm sure I'd be doing better. That said, I also have an exhaust, intake, and tune that all affect it somewhat.

[MxRider801]

Why is the 5.3 mileage so low? I get about that in my truck.

 

I think they are only rated 14 city and 19 highway IIRC.

 

So far I have calculated 2 tanks in mine. One was 90% city with two trips on the freeway at 80mph and 30mph stop and go. The result was 14.8 mpg. The second time was pulling a trailer and 4 bikes out to the desert at 75-80mph and I only netted 13.4mpg. The trailer was bit "off" as the wheels wobbled and it made all sorts of noises. But I wasn't too impressed.

 

If the DIC is correct the truck has a average mph of 17.0 for the life of the truck. I just got her a couple of weeks ago so i'll have to see what I can do during normal driving conditions. Also, i'm comming off of a hopped up duramax so i still have to change my driving style a bit.

[High Plains Drifter]

I get 18 mpg combined consistently. '08 Silverado 5.3.

[fbachman]

I get 14-15 city 17-18 highway with (3.73 in the back).

 

I'd like to know how you guya with the 5.3 and the same gears I have are getting 17 mixed. I would be gleeful with that.

 

DOn't get me wrong. I have a huge truck... I consider 14-15 acceptable, GIVEN THAT IT"S A TRUCK.

[rogerf]

I just ran my '07 NBS Z-71 reg cab 4X4 (5.3L w/ 3.73's) on an 830 mile expressway drive yesterday. The majority of this was 70+ mph and mountainous (WV Turnpike & I-64 into VA and back). Was able to segment the hardest running conditions to 17.4 mpg overall (547 miles on 31.4 gal). The remainder was flatter segments in Ohio which averaged 21.3 mpg. Overall was 18.7 mpg for the entire trip. Checked the accuracy of the DIC vs. the pumps...was dead-on.

[fbachman]

Checked the accuracy of the DIC vs. the pumps...was dead-on.

 

That surprises me. Mi DIC is about 7% optimistic overall on MPG. I have often wondered whether something is off, as my DIC has been significantly off since I have owned this truck.