MPG numbers from 5.3L Silverado 1500?

[NHHEMI]

Originally Posted By: Blue_Goose
Looking for some real world mpg #'s from Silverado/Sierra 1500 owners that have the 5.3 engine.

I would not expect great numbers from around town but anything I have read has been people getting 10-14 mpg and that is including highway.

I drive 100 miles a day r/t almost 99% highway, just looking for some stats from people who actually own this vehicle....currently looking at with a 2000 Silverado and a 2004 Sierra 1500 SLE


Goose


I had a 2005 Silverado 1500( GMT800 ). It was an Extended Cab 4WD w/ the aluminum HO 5.3L( 310HP vs the standard iron block 295 - only available on EC's w/ 4WD ). It had 3.42's and 265/70R17's. I saw 14-15 MPG city, 17-18 MPG average for mixed driving, and usually 20-21 Highway with a best ever of just under 24 MPG. Hands down the best truck I ever owned for MPG. Sadly it was thrashed by a massive hail storm and the insurance company screwed me over like so many others in the area and it was not fixed properly so I didn't keep it long. Very nice truck though and the MPG was great.

Just for comparison sake in case you look at the newer Silverado's( GMT900's ). I replaced the 05 with a NBS 2007 Silverado 1500. It too was an Extended Cab Z71 4WD w/ 5.3L. It had 3.73's and 265/70R17's. Despite the AFM thhat was supposed to increase MPG the truck saw significantly worse MPG. Some of it is the 3.73's vs the 3.42's but not all. GM's AFM and Dodge's MDS just does NOT work on big heavy trucks. IT may in theory but not in the real world. The MPG was 1-2 MPG lower across the board for the 07 Silverado vs the 05 I had. I only broke 20 MPG highway with it once as I recall and that was barely.

 

[SteveSRT8]

It's interesting that you commented on the 3.73 gearing, as in our fleet the one truck with the 3.73's actually gets the best city mileage of them all!

 

[spasm3]

since my avalanche is mostly used for towing, i've had the inkling to put 4.56:1 gears in it. Its 4x4 so i'd have to do both diffs.

 

[Rhymingmechanic]

Currently 11.5-12.5 city, 17.5-18 highway.

I have a 2001 2WD regular cab shortbox with 3.42 gears. Mileage has gone down since my most recent move, about 17.5-18 doing the speed limit on interstates here in the overcrowded Mid-Atlantic and points south. I think that may have to do with ethanol as well as traffic. The 5.3 will have power to pass.

City-only mileage is down around 12. My previous commute averaged 17.5. That was 18 miles each way, about half city and half 45-55 mph suburban and rural 4-lanes, and no ethanol. I try to drive like a guy who cares about money but is feeding a V-8 on $3-$4 gas.

Out west, it used to get 19.5-19.8 at 75mph with the air on. At 65 on the back highways it could get better than 21. My wife has gotten 21-plus more than once on the interstates, following a moving truck.

Is the Z71 you're looking at lifted? My brother had a '99 with a lift kit, and it kept eating driveshafts. I can't remember whether they were front or back.

 

[FZ1]

The ethanol reduces mpg by 10-15%.

 

[NHHEMI]

Originally Posted By: SteveSRT8
It's interesting that you commented on the 3.73 gearing, as in our fleet the one truck with the 3.73's actually gets the best city mileage of them all!


And that was all I heard when I had it and was on the GM forums. Didn't work that way for me. Had same issue with my Ram's and 3.55's vs 3.92's. Everyone claims the 3.92's get better MPG but not for me. Not towing or non towing and not city or highway.

 

[SteveSRT8]

Originally Posted By: NHHEMI
Originally Posted By: SteveSRT8
It's interesting that you commented on the 3.73 gearing, as in our fleet the one truck with the 3.73's actually gets the best city mileage of them all!


And that was all I heard when I had it and was on the GM forums. Didn't work that way for me. Had same issue with my Ram's and 3.55's vs 3.92's. Everyone claims the 3.92's get better MPG but not for me. Not towing or non towing and not city or highway.


Yeah, I wouldn't have believed it either, but there it is in my driveway.

Real world mpg has so many variables that it is almost impossible to compare except through EPA ratings. Since the biggest one is the driver and we're all different...

 

[NHHEMI]

Originally Posted By: SteveSRT8

Yeah, I wouldn't have believed it either, but there it is in my driveway.

Real world mpg has so many variables that it is almost impossible to compare except through EPA ratings. Since the biggest one is the driver and we're all different...


Yup, it is the driver. I agree.