What Kind Of Mpg Does Your 6 Speed 5.3 Get?

[JeffM.]

I currently have a 2005 Avalanche with 3:42s, 4x4, and the 5.3L. It is setup to get some good mileage but I find it weak in towing strength due to the lack of gears. So I am thinking about picking up a new Sierra with the 6 speed transmission again with 5.3 and 4x4, I am wondering what kind of mileage people have been getting with it so far. I typically get better than EPA highway mileage, so I’m wondering if I can really get the 21mpg the Sierra offers. How well has everyone else been able to attain?

 

TIA,

Jeff

[leverlution]

2010 ext cab 6.5ft - 5.3 LC9 Aluminum AFM - 6 SPD - 3.08 Rear - 4x4 - 17in wheels - Goodyear STREET tires.

 

~16.5-18.5 Average depending how I drive it. Got 19 AVG on tank trying.

 

19-25 Highway. Really depends on how hilly it is. If it's real flat, I can see 24-25 with cruise on at about 60. Usually average 20-22 highway in "normal" conditions.

 

19 going through WVA highways with cruise set at 75.

 

Everyone is going to be different. Every area of the state will be different.

 

Typically, a Silverado will see better MPG than an Avalanche. 6spd and 3.08 is pretty equivalent to your 3.42 and 4 speed I think from what I have read. Slight dead spot at the beginning of 2nd if you are driving for MPG and let it shift out of 1st between 2-2600rpms. Above that and it's just fine. Would probably go for lower gears if I was going to be constantly towing though. You'll probably be in the gas more than you would like with the 3.08s and towing. Certainly nice running 1600rpms on the highway though, and the 3.08/6spd was AWESOME driving the old oil roads (quads use them for wheeling) up in the WVA mountains. No complaints at all, other than 4LOW on decent, but I came off a 4.10 4:1 Jeep.. I was kind of expecting a difference in downhill :-D

[426ted]

Not that good. if you go over 55mph, expect it to suffer. Mix of highway (flat too, mind you) and city (not slow stop and go either), I average 15mpg. Quite a bit less than what is advertised, as I figured it would be. If I stick to the speed limit and avoid highways where the speed limit is 100kph, I can get 16mpg and that's it. Pushed it hard into the mountains the other week (only steak, beer and a tent to weigh me down) I avearged 12.1 mpg. Beat on it though, so I didn't expect much. Boy did I laugh. Found out the pig won't go over 160kph. On the way home, i averaged 14.5mpg-funny as most was downhill. I think mine is a rare case, as there are a lot of members here who claim to get good mileage and drive faster on average than I do. Who knows, maybe the gas companies are mixing in more than the 10% ethanol stated.

[Heavyiron]

15 - 17 MPG in town

 

Just got back from 600 mile round trip to San Diego -

Freeway @ 75 - 79 MPH = 16 - 17 MPG (hand calculated).

[JeffM.]

25mpg, that is incredible out of a half ton! My best in my Avalanche was 22.4mpg, that was due to being paced by construction. All around I'm probably 18-19, which is about the same as my previous GMT800 trucks.

 

I think I read that the final ratio was 2.79 vs 2.29 on the 4spd vs 6spd with the same rear end. I would think that your 3:08 should be spinning some pretty low RPMs compared to my 4spd 3:42. I don't tow very often but it just seems like the 4spd has a huge gap between 3rd and 4th, constantly shifting to keep pace up over 65mph with a big trailer. 4th didn't have enough power but 3rd was winding the RPMs up so high that it kept shifting back.

 

On a long unloaded trip I was going 75-80mph and got low 16s, so it looks like I may be able to pick up a couple mpg?

 

Yea, I heard there is a 100mph limit on them... kind of lame although I rarely get cooking along that quickly.

[Z45]

I have one of these trucks (5.3L and 3.42) and I just can't see how these owners come up with 22+ mpg unless they are coasting down hill when they come up with these numbers. I think some of their calculations needed to scrutinized.

 

The best I am at is 18.5 and I never speed, take off like a drag racer or anything. I know 2 other guys with same trucks and they are right in the 18's like me. Btw- 18.5 is average of approx 5,000 miles not 100 miles down an down hill grade.

[JeffM.]

Elcamino, is that hand calculated from all of those fillups or from the computer? Was that when it was warm out? My truck seems to be get very low mileage while warming up but after that it gets better. The dash on my Vette says I get 30mpg all around and 33mpg on the highway... it is ~10% above the real number, my truck was claiming to get 19mpg in the winter... when it was really getting 15-16 due to all of the warm ups.

 

It is looking harder and harder to get the EPA number of 21mpg highway.

[leverlution]

I have one of these trucks (5.3L and 3.42) and I just can't see how these owners come up with 22+ mpg unless they are coasting down hill when they come up with these numbers. I think some of their calculations needed to scrutinized.

 

The best I am at is 18.5 and I never speed, take off like a drag racer or anything. I know 2 other guys with same trucks and they are right in the 18's like me. Btw- 18.5 is average of approx 5,000 miles not 100 miles down an down hill grade.

 

You are comparing 2 different figures. I am at 18ish average, just like you. I said 22 *HIGHWAY*. Pure highway, cruise on, windows up, AFM doing it's thing etc. You can say I'm lying all you want, don't bother me one bit. I'm 25 and married, living in one of, if not THE most expensive places in the country. I have a tight budget, and I'm well aware of what I pay for in gas. Have you considered the fact that I said 3.08 rear, and you have 3.42s? Probably not.

[leverlution]

Not that good. if you go over 55mph, expect it to suffer. Mix of highway (flat too, mind you) and city (not slow stop and go either), I average 15mpg. Quite a bit less than what is advertised, as I figured it would be. If I stick to the speed limit and avoid highways where the speed limit is 100kph, I can get 16mpg and that's it. Pushed it hard into the mountains the other week (only steak, beer and a tent to weigh me down) I avearged 12.1 mpg. Beat on it though, so I didn't expect much. Boy did I laugh. Found out the pig won't go over 160kph. On the way home, i averaged 14.5mpg-funny as most was downhill. I think mine is a rare case, as there are a lot of members here who claim to get good mileage and drive faster on average than I do. Who knows, maybe the gas companies are mixing in more than the 10% ethanol stated.

 

Holy crap!! Do you have a 6.0 or 6.2? Do you leave 4x4 in "Auto" and not 2wd? Lot of stuff in the truck?

 

Geez, you are talking like Nissan and Dodge mpg!

[vettelovralexand]

I usually get an average that is somewhere in the 14s in town and somewhere in the 17s on the highway. My overall average is now right at 16.5. Even with the tune I have not noticed much if any of an improvement, but I have been spending more time in town since then so I haven't really had a good comparison drive since.

[b00001]

My last 3 tanks, I have been over 20 MPG! 20.1, 20.2, 20.09. I am a on road rep so I am on hwy mostly (70-72 mph) but then have to get off hwy and go through towns to customers. Some is 2 lane hwy with full throttle passing. Just hit 10k miles so hoping mileage will get better when I go to synthetic oil.

 

2010 Silverado, ext cab, 3.08 axle, 18" wheels. Have a tonneau but doesn't seem to matter if it is open or closed.

[Dmart11]

I am getting 19.9 according to the DIC after 6k on her. I drive 50 miles each way to work with a mix of country roads and 2 lane highways here in eastern NC. I am also running Mobil 1 syn. Pretty good if you ask me for such a heavy truck.

 

This is on my Z71 (2wd) CC 5.3 6sp w/ 3.08

[DwelveAT]

With a 6" lift and 35s, according to the DIC, I get an average of 14.5.

 

4wd Z71 CC 5.3 6sp w/ 3.42

[tomr80]

Best of 18.5, average 17 flat I don't "hot rod" the accelerator of anything like that. BUT, i still have the cheap 4ply "car" tires still on it. I imagine all that will change when I put some real tires on! Since good tires now a days are 8 to 10 plys, I'm gonna lose some mpg! Oh well, all the price you pay to own a truck I guess.

[Harvey Halabookie]

14-16 MPG on the street.

 

18-19.5 highway.