Biochem

So this is about the third long trip that I've tried keeping track of my mpg. This was all highway miles, doing about 80mph the whole way (around 1800rpms), and the outside temps were near 35F and clear skies. The trip was 234 miles and took about 10 gallons of 93 octane each trip. My math, that comes to 23-24 mpg... shouldn't I be more like 28? My old 84, with a lot more HP motor and a q-jet, used to get 25mpg... I thought FI was supposed to be so much more efficient <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> BTW- the only mod so far is a lid/holley air filter and a descreened MAF. Tires are even inflated to 35psi...

Iv_z28

I heard many times that people are getting up to 30+ mpg on a highway, and one person I know actually made a goal of finding out the mileage at 65mph - it did turn out ~28-29mph on his car, though under normal highway driving he was getting ~25mph.
I'm also getting ~25mph on highway trips. Unfortunately I never tried going below 80mph on a long trip and on my last trip from Tucson to San Diego my average speed was ~95mph... so the mileage sucked <img border="0" title="" alt="[Frown]" src="gr_sad.gif" />
Don't worry, it's even worse at 150+ mph <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> <img border="0" alt="[evil]" title="" src="graemlins/gr_devil.gif" />

joghotrod

How many times did you romp on it to pass some slopok in the left lane? If you did, that will kill your miles per gallon. But it is fun. Jimmy

Tim 98z

iTrader: (1)

That sucks. I got 25MPG out of my car on my trip to Texas two weeks ago. With a cam ORP and 4.30 gears in the 12 bolt!!

zTrackerz

I have a 2000SS M6. A few Mods.. I just recently took a long trip. Actually a few trips (1600 mi). I got about 24 MPG. The city I usually get about 16 MPG..........

deviate42

iTrader: (2)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Tim 98z:
<strong> That sucks. I got 25MPG out of my car on my trip to Texas two weeks ago. With a cam ORP and 4.30 gears in the 12 bolt!! </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif"><img border="0" alt="[jester]" title="" src="graemlins/gr_jest.gif" />
what rpm are you at highway speed?

Tim 98z

iTrader: (1)

It's not bad at all really with the 6 speed. Like 2100@70 (yea like i was really doing 70 most of the time <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> )

XFiveLiter

Is this a brand new car? How many miles are on it? Your car will make more power and get better MPG after about 10k.

DONAIMIAN

iTrader: (18)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by XFiveLiter:
<strong> Is this a brand new car? How many miles are on it? Your car will make more power and get better MPG after about 10k. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">takes that long for your engine to get to max power and better MPG, I thought it was like 2k <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

jmX

I had a cam in my car, I drove from portland oregon to texas and got 34mpg average. Something isnt right if you only got 24.

Biochem

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by XFiveLiter:
<strong> Is this a brand new car? How many miles are on it? Your car will make more power and get better MPG after about 10k. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">The car is less then 1 yr old and I am about to do my 4th oil change on it (~12K miles)...

Gold Phoenix

iTrader: (1)

I get 27-30mpg on my trips from Lafayette, LA to Indianapolis, IN. My max speed is 75mph. If I have to turn off the cruise control for a slow poke, I slowly bring the car back up to speed before I turn it back on. The cruise what to dump the throttle to get back to the set speed. Also, tire pressure can be a factor. I pump the tires to 40psi for less rolling resistance. Here is all my mods too.

absolut_speed

iTrader: (1)

I have to try my hardest to get 23mpg over a full tank, all highway.

2002 M6 Firehawk - No mods
72-73mph over a full tank, no A/C, no stops, no in-town.

Dealer won't look at it until I get to 10,000 miles. Says it seems normal and mileage should improve by then.

XFiveLiter

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Biochem:
<strong> </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by XFiveLiter:
<strong> Is this a brand new car? How many miles are on it? Your car will make more power and get better MPG after about 10k. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">The car is less then 1 yr old and I am about to do my 4th oil change on it (~12K miles)... </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Your motor is plenty broken in then, I dunno <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

XFiveLiter

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by stang killer:
<strong> </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by XFiveLiter:
<strong> Is this a brand new car? How many miles are on it? Your car will make more power and get better MPG after about 10k. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">takes that long for your engine to get to max power and better MPG, I thought it was like 2k <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">LS1s have very tight bearing clearances when new. Some folks have dynoed slightly higher w/no new mods as the miles rack up.

disclamer: This is not from personal experience, but just what I've heard.

John B

iTrader: (10)

Well look at the positive side of things....I have a complete S2 package with all bolt ons and 4.10's and get 24 MPG on the highway so you shouldn't expect to lose much when the mods come!

SS Mark

Thats wierd, a few years ago on the Hot Rod Power Tour my dads 6-speed SS got about 29 mpg, and trust me we had quite a few "romps" on the gas pedal <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

YankeeSS

I wouldn't sweat getting 22-24mpg. I mean, its absolutely great that a 330+ HP car can achieve such efficiency. Maybe since you are so concerned with mileage, you can trade the car in for a Civic Hybrid? <img border="0" alt="[jester]" title="" src="graemlins/gr_jest.gif" />

miner_49

I have a '02 WS6 w/M6. I average 24.4mpg. But I get this while commuting 22 miles one way to work on the freeway going 80mph mixed in with some stop and go traffic and a few miles of surface streets. And I'm not exactly taking it easy on the accelerator.

If you are only getting 25mpg with only highway driving (not alot of traffic) then its 1 of 2 things:

1) You are giving it more gas on the accerator than you think (you shouldn't be out accerlating anything except a civic or you car is going to eat gas). If you gear isn't forcing you to shift into 4th from 1st, then you are giving it too much gas.
2) Or your car isn't tuned correctly/something is wrong with it. What mods if any do you have?

CW 99 Z

Dont take this the wrong way Biochem, but I laughed a little when I saw this post. I used to drive a 72 nova with a 383 stroker, A3, and 4.10 gears. The best I ever got was like 7 mpg. This motor put 460 hp to the crank which is about the same as what most H/C LS1 put down, maybe even a little less. My point is, if you can get over 20 mpg with a 350hp car be happy. Hell, most family sedans with v6 motors would do good to get over 25 mpg.