GM 5.7 L MPG

[mjk]

Hello,
Before the inevitable 'you don't buy a truck for MPG' response comes out, please hear me out.

I am looking at a 1998 GM Sierra in a few days. I'd like to hear what people are getting for HWY mpg. My driving style is very conservative. In MN, most of the interstates are 70. I typically set my cruise around 67 or so, and stay in the right lane.

I ask, as I am getting wildly varying reports when doing a Google search. I am sure part of it is the nature of those driving trucks, and varying sizes of tires, etc.

Thanks.

What I am hoping to hear is 17-18 MPG. I am not sure of this truck's rear-end, but going to guess it has the 3.73 gears.

If I have the VIN number, is it possible to research this online?

 

[silverrat]

You can check fuelly.com for user reports

 

[NHGUY]

15-16 more likely.A more modern 5.4 Ford or 5.3 GM will do around 16-17,if you're lucky.Hemi RAM when you're on it...14 at best.

 

[bullwinkle]

My departed C1500 '94 Suburban, when driven conservatively (on vacation), could achieve 17 MPG (350 TBI, 4L60E, 3.42 rear axle), and tipping the scales at over 5000 pounds loaded-so it can be done. With summer fuel, of course, in winter there's no way!

 

[supton]

Try here: http://www.compnine.com/vid.php

IIRC you have to register, then you get like 10 free, then it wants you to pay. Something like that, been a while.

You can also ask to get the RPO codes off the glovebox door. I'd write down the rear axle ones; it's like GUx where x changes. A number of sites list the axle codes.

 

[jeepman3071]

Originally Posted By: NHGUY
15-16 more likely.A more modern 5.4 Ford or 5.3 GM will do around 16-17,if you're lucky.Hemi RAM when you're on it...14 at best.


I'd agree with this and say 15-16 mpg.

A newer truck will likely get better fuel mileage, but initial purchase price will also be higher.

 

[morepwr]

My 91 2WD extra cab would get 18MPG and had the 3.42 rear gear. Much harder to do with the 3.73 rear unless you keep your speed down. I usually go 70 on the highway.

 

[Gabe]

My Dad has a 2500HD with the 5.7 and a manual transmission. Combined is a little under 14 mpg. If I baby it, I can get around 16 mpg. Driving 70 down the interstate, you should expect 15 mpg.

BTW, great motor to work on.

 

[dernp]

You also have to realize this truck is 16 yrs old.

 

[billythekid]

14.4 mpg in my 98 suburban 5.7 with 20 inch wheels on it. That was a NY to DC trip and back.

Sub 10 mpg (actually around 8) doing around town driving.

 

[mjk]

Here is the truck...

http://minneapolis.craigslist.org/ank/cto/4301139569.html

 

[gregk24]

Our 99 GMC Suburban got 18 on the highway with a cargo carrier on the roof with 8 people inside.

 

[supton]

Originally Posted By: mjk
Here is the truck...

http://minneapolis.craigslist.org/ank/cto/4301139569.html


Interior looks a bit aged, but it's shiny on the outside. Trim lines up looking down the truck, so the cab corners are probably good. Looks ok.

Says transmission is rebuilt. I'm never sure what to make of that. Was it rebuilt with better parts? Was the cooler properly flushed after whatever failed? And what failed in the first trans anyhow? Clutches plain worn out, or did something grenade and generate shrapnel?

 

[mjk]

The current owner works at a GM dealership here in Minneapolis. He bought it from a customer, at the time the transmission was shot. The dealership did the work - the owner is a salesman there, it was a 3rd vehicle for him.



Originally Posted By: supton
Originally Posted By: mjk
Here is the truck...

http://minneapolis.craigslist.org/ank/cto/4301139569.html


Interior looks a bit aged, but it's shiny on the outside. Trim lines up looking down the truck, so the cab corners are probably good. Looks ok.

Says transmission is rebuilt. I'm never sure what to make of that. Was it rebuilt with better parts? Was the cooler properly flushed after whatever failed? And what failed in the first trans anyhow? Clutches plain worn out, or did something grenade and generate shrapnel?

 

[Nick1994]

I owned a 1996 Chevy with the 5.7L Vortec and 3.73 gears for a few years. It got 15.5-16 mpg max in the city and the best tank on the highway was 17.5-18 mpg. Driving like an old lady and driving pretty quick didn't. Are much of a difference for city driving, it always got the same pretty much. I loved it and hated that I sold it, it had a fantastic engine with more power than I ever would have needed. Good luck!