3.73 Axle ratio and gas mileage

JChrisBullard · February 12, 2003

I have 2001 4wd silverado with 3.73 ratio, I have heard that they get horrible fuel mileage, and should have purchased a 3.08 or 3.42. I has the vortec engine in, does anyone have any info. Have not burned a tank out of her yet, but just kinda concerned about it. Thanks.

TomEllis · February 12, 2003

I have heard that they get horrible fuel mileage, and should have purchased a 3.08 or 3.42.

This is compared to what?

I have a 2002 2500HD Crew Cab with the 8.1l (496 cid) and the allison transmission and 3.73 rear end gears. I get good gas mileage for a large vehicle. If you wanted to get 25-40 Mpg, then you should not have bought a large truck. I am not trying to be mean or bad mouth you, I just do not know what is meant by "horrible gas mileage".

If you think that your truck is a good truck and you bought it to haul stuff in the back or to tow something, then you purchased the right vehicle.

good luck,

Tom

nhkid28 · February 13, 2003

On my last tank of fuel I averaged 17 mpg and this is with highs in the 20's. Which was about 540 miles to tank. Last summer I had a few tanks of 19+ which was almost 600 miles for the tank.

I have the 34 gallon fuel tank.

Tweeter400 · February 14, 2003

I do about 80% city miles and I average about 14mpg if I keep my foot out of it!!

carguru · February 14, 2003

You trade off a lot between payload and mileage. I have the 3.73 with 5.3L 4x4 in sig. 14-15 all city. 19-21 highway. The 3.08 might make the truck seem a bit weak at takeoffs. I did an unscientific comparison on 2 '99 2wd 5.3L trucks. One had the 3.42, the other with 3.73. The results gotten were that there was only 0.2 mpg difference between the 3.73 and 3.42 over 20k miles. I wouldn't worry that much. At least you don't have a Dodge that gets around 10-12 mpg. :thumb:

BlueRado · February 14, 2003

I wouldn't be too worried about the 3.73. I had a '99 1500 LS 4x4 5.3L w/ the 3.73, and I averaged 15 mpg in city and 18 mpg hwy. In Winter (Michigan) I got 13-14 mpg city.

In the heat of the Prairie Summer I went across Okla doing 80 mph w/ the air on and loaded back for camping w/ a topper and got 19 mpg on one tank.

I have the 4.10 now on my '03, and so far looks like it will get about 1 mpg less city and hwy than my '99 did. I'll know for certain this Summer.

I like the oomph you get from the 3.73, and especially the 4.10, so it's worth it for me even with a little lower mileage, plus you can tow more and do it more easily.

BTW, welcome to the site - this is a great place to hang out and learn!! :thumb:

JChrisBullard · February 15, 2003

Thanks for the replies, got through with my first tank and it ended up with about 16.6 mpg, which I am happy with since I am looking at the Dodge that I drove for 6 months and bout broke me with 11.6 mpg.

BlueRado · February 15, 2003

:thumb: :thumb:

denali_dave · February 27, 2003

I dont think any of you should even think about complaining. I am getting 10MPG city with my wife driving and 13.3 hwy going about 80 most of the time on flat interstate. I cant believe this vortec 5.7 is getting this pitiful mileage. My 94 TBI 5.7 got 15/17mpg but it was 2WD. 4WD cant be making that much of a difference. Any suggestions besides the tune up I am getting ready to try?

JChrisBullard · February 27, 2003

No more complaining here, I left a Dodge at 10-11mpg, and finally burnt my tank out and ended up with 17mpg, so I am good to go. That is what my buddy also gets out of his Yukon. We have the same engine, I guess it is a lot heavier vehicle. I went through the gas mileage battle with the Darn Old Dirty Gas Eating DODGE, filter changes, timing, plugs, brass rotar, wires, dist., cold air intake, K & N, I never saw any improvement in mileage. I hope that you find some relief, there are some smart people hanging around the site here that may have the silver bullet you are looking for, I tried every mod everyone could think of with that vehicle and even contemplated changing to a fuel vaporization system which is 200 bucks, but gave up. It was cool trying all of those things, just wasnt cool giving up the bucks to try and save them. Good luck and stay at it.