Why bad gas mileage?
#1
TECH Fanatic
Thread Starter
iTrader: (25)
Join Date: Jan 2006
Location: Katy & College Station, TX
Posts: 1,271
Likes: 0
Received 0 Likes
on
0 Posts
![](https://ls1tech.com/forums/images/ranks/ls1tech10year.png)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Howdy! I have a 02 Z28 M6 with lid, loudmouth, and skip shift only. I recently changed the oil and seafoamed the gas tank and through the brake booster line. I used to get between 15 city and 19.5 highway when bone stock which i thought was just pitiful. I now get 16.5 to about 20.5.
Why am i not seeing what you guys are getting (18 city and 24 to 26 highway)? I tend to drive it easy and even when i try not to rev above 2000 rpms, i still don't get great mileage! I have about 81k miles. I used to have a bad cat when i bought the car which was driven about 8k miles with a SES light on by the ***** before me. Could it have fried my 02 sensors or something? When i bought it i had the injectors flushed and everything.
Why am i not seeing what you guys are getting (18 city and 24 to 26 highway)? I tend to drive it easy and even when i try not to rev above 2000 rpms, i still don't get great mileage! I have about 81k miles. I used to have a bad cat when i bought the car which was driven about 8k miles with a SES light on by the ***** before me. Could it have fried my 02 sensors or something? When i bought it i had the injectors flushed and everything.
#5
TECH Fanatic
iTrader: (1)
Join Date: Apr 2006
Location: Fort Worth / Crowley / Burleson, Texas
Posts: 1,097
Likes: 0
Received 0 Likes
on
0 Posts
![](https://ls1tech.com/forums/images/ranks/ls1tech10year.png)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
sucks to be you dude. My Z is totally stock (not for long tho) and I get 24 i the city and 30-33 on the highway. And having to put premium in it to @ $2.91 a gallon.
#6
Launching!
Join Date: Sep 2005
Location: Arlington, VA
Posts: 263
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Originally Posted by Splitz
sucks to be you dude. My Z is totally stock (not for long tho) and I get 24 i the city and 30-33 on the highway. And having to put premium in it to @ $2.91 a gallon.
![Sad](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_sad.gif)
#7
TECH Fanatic
Thread Starter
iTrader: (25)
Join Date: Jan 2006
Location: Katy & College Station, TX
Posts: 1,271
Likes: 0
Received 0 Likes
on
0 Posts
![](https://ls1tech.com/forums/images/ranks/ls1tech10year.png)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
yea im at about 3.15...i still have ext warranty so ill see if i can coax the dealer into getting me some 02's...that wouldn't be considered normal wear and tear like brakes would it?
Trending Topics
#9
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
My 98 SS M6 gets 21-23 around town and 26 on the highway. Use mid range, you may get a little better mileage, when I use it I get a couple miles better per gallon. Stay away from the premium, it costs too much and is dirty, your plugs won't like it.
#10
TECH Junkie
Join Date: May 2003
Location: its fucking cold
Posts: 3,050
Likes: 0
Received 0 Likes
on
0 Posts
![](https://ls1tech.com/forums/images/ranks/ls1tech10year.png)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Originally Posted by Corvetteman78
Use mid range, you may get a little better mileage, when I use it I get a couple miles better per gallon. Stay away from the premium, it costs too much and is dirty, your plugs won't like it.
#11
TECH Enthusiast
Join Date: Oct 2005
Location: Miami, FL
Posts: 595
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
I dunno how it can happen but if cats get dirty enough they can cause horrible gas mileage. I know of a V6 that jumped like 5 mpgs by removing em... pretty crazy.
I'm not sure why your highway is so low, but your city is very decent.
I get a measely 13 city, not even 200 miles to a tank. But my highway is decent at 22-23. Too bad I do at least 90% city.
I'm not sure why your highway is so low, but your city is very decent.
I get a measely 13 city, not even 200 miles to a tank. But my highway is decent at 22-23. Too bad I do at least 90% city.
#12
Launching!
iTrader: (2)
Join Date: May 2006
Location: Kansas City, MO
Posts: 274
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Originally Posted by Splitz
sucks to be you dude. My Z is totally stock (not for long tho) and I get 24 i the city and 30-33 on the highway. And having to put premium in it to @ $2.91 a gallon.
#14
TECH Apprentice
iTrader: (5)
Join Date: Apr 2005
Location: Arlington, Tx
Posts: 337
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Even with the mods I have and the car is untuned, i get 300 miles per tankful.
It is 75% highway, 25% local. I have changed everything Choco mentioned very early in the 1 1/2 years I have owned the car....maintenance is everything.
I paid $3.06 today for premium.
It is 75% highway, 25% local. I have changed everything Choco mentioned very early in the 1 1/2 years I have owned the car....maintenance is everything.
I paid $3.06 today for premium.
#19
TECH Fanatic
iTrader: (1)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Originally Posted by jmm98LS1
Nope. Higher octane = more resistant to detonation.
Does it make up the 10-12 cent per gallon difference? Maybe, maybe not.