I just filled my tank, and the better portion of the tank was spent travelling highway, i would imagine...some stop n go, some highway.

roughly 20-21mpg.

I'm wondering why this could be, i have a 2000 that just rolled over 38k miles. My brother's 1998 77k mile, similarly equipped/modded LS1 gets ~24.

My mods are a G2 lid and G2 maf sensor on the intake side. Here's a few things: the G2 lid comes with a breather for the AIR pump. Could that reduce MPG because of lack of that air coming in? As well, I've heard good and bad about the G2 maf sensor...I'm still somewhat new to LS1 mods, so bear with me...can anyone offer some help?


I also have a flowmaster exhaust system, if that helps any, and !cags.

 

its2 ppl driving, anything 20+ id say is good.... its a big engine..... see how he drives.... and each car is different...
cory

 

Even 21 with mostly highway driving is terrible. Theres something wrong. Get the computer checked out by a dealership first...check your oxygen sensors and stuff.... I don't know enough about mechanical stuff to tell you whats wrong, other than thats pretty bad for mostly highway driving...

 

how are you two comparing info?

My insanity.. yes I log it all..
and even save it to html... great! hehe

Today I added to my spreadsheet. It now calculates average cost per mile. (.10¢).

You two are both getting better mileage than me. But I drive "sprited" as some would say.. Others say I drive more "psychotic" hehe..

Then again.. I deliver pizza in my car.. hehe

 

I'm getting about 17-19 mpg in normal city driving around me. Don't think that's to bad, drive it nice and easy most of the time. But then theres those days where I drive it more spirited.....

 

Just around town I'll always get around 18.5. One a few pure highway trips, I got 25-26. This was all done with a heavy foot too. If I drove it easier I could get more out of it.

 

6th gear, on the highway, 75 MPH, 1800 RPM = 30.5 MPG with SLP Lid, Magna Flow Catback, 85 MM SLP MAF

 

Don't feel bad, I get like 16 MPG in mostly city driving. That's really bad considering I usually shift at like 2300 RPM.

 

also it's the summer season so the a/c is on often?

 

use shell gas, clean your injectors, and drive slow...dont rev past 2k if you can help it...if your car is an m6 use 5th gear after 40 andi now get an amazeing 22 mpg city