27 MPG on the freeway---17-20 around town-----avg. 22

Thats with 390 RWHP, 2600 stall, 3.42 gears---long tubes--
And with a tune--getting the fuels trims in line close to "0" --adding as much timing as I could without KR in the cruising ranges & getting the O2 switching points around .430-.450 Millivolts and making sure the commanded closed loop AFR of 14.68 matches the actual----(with a wideband)---

:iagree: I just made a 1400 mile round trip journey from South Florida to North Georgia- Average 80MPH and 28.7MPG on the highway stated the cars computer. I even calculated 28.5 by doing the math at the fill up points.

My car is a 97 6 speed- when you are at 80MPH, I am still turning less than 2K RMP's in 6th gear.

I also average 21 - 22 around town (granted you have to keep your foot out of the skinny pedal!)

These figures are right up there with the 03 Honda Accord 4cyl I had as my Daily Driver! now I drive the vette 60 miles round trip to work everyday...

Great cars!:thumbs:

I know a lot of people are gas mileage wary but there aint no way id every drive in the city in 5th gear and NEVER 6h gear lugging it around at 1000 rpm. I mean cmon thats just ridiculous. I very rarely ever get out of 2nd-3rd in town driving usually between 35-45 and keeping rpms in the 2500-3000 range cruising in any gear even on the freeway.

Average 22 23 in town and 28 30 on the road on the DIC, but do it the old fashioned way Miles divided by gallons and the Dic is usually off 1 2 MPG + or -.

Flat road Cincinnati to Columbus Cruise on 72 with air on I get approx 33.4. The Instant Average reads 29 - 39 constantly.
Best milage was going into Albuquerque NM on 40. Was catching a storm from due West 60 mph average winds. Averaged 72.8 mpg for over 40 miles.:rofl: Had to be the big butt I guess. Used Cruise to keep the speed at 75. Lota wind, some rain and a lot of dust. Woke up in the a.m. and headed directly to the car wash to remove silt from the back of the car. It looked like pottery clay.:thumbs:

Fuel usuage is dictated by CAFE standards (FED. Govt.) Corp.Avg.Fuel Economy this allows for every gas sipper theres a gas guzzler which in chevy's case the gas guzzler is prob. the surburan not the vette.The cars are set to acheive the best milage @ 55 mph which is (was??) the national speed limit. In my case it proved to be true,03 z/06 180 mile all hi way but w/numerous hills (upstate N.Y.)I got 28mpg around town driving the way a corvette should be driven (spirted) I still got 21.If you're totally obsessed W/fuel milage,install a vacuum gauge and try to keep the engine vacuum as high as you can in addition drive like there was an egg between your foot and the gas pedal and try not to break the egg.Lest we forget the corvette first and foremost is a hi performance car and to achieve the mileage they do get is quite remarkable.

I get 28 to 31 on the highway, with normal driving, not spirited. I get 19 to 23 in town.

The range in town depends on what type of in town driving I do. When I drove it do work, I had more freeway type driving than side street, therefore a higher number. When I did short trips, stop and go then it goes down lower. I believe the reason most people give different numbers is the different type of driving and different routes.

I have noticed that I get better milage on the highway when I keep it above 1600 rpms. In a 6-speed that puts you real close to 80.

Also DO NOT BUY gas in Louisville KY. We have that reformulated crap gas. I always get lower mpg on our gas than when I get out of town and can get real gas. I have proven that with every car we have owned over many years (Lexus, Z-28, Buick GN, Buick Regal Grad Sport, even my 4 cyc Ranger to name a few). The fool EPA idiots can suck a lemon, because they are wrong in stating that it does not effect milage.

I find that the fuel mileage computer is about 2 mpg too generous. My driving basically has about 5 miles of 35 mph neighborhood driving, 10 miles of rural 55 mph speed limit roads, 15 miles of multilane 70 mph highway, and 10 miles of suburban/urban driving. With this profile I get about 27-28 mpg, calculated off mileage and gas receipts. Engine/drivetrain is completely stock.

One thing that affects mileage significantly is what gear you use. I go into 5th around 35 and 6th around 45-50. I have friends that consistently spin their engines up over 1500 rpm all the time, and their mileage suffers accordingly.

HTH, and have a good one,
Mike

BTW, if you run 10% ethanol fuel you'll see about a 2-3 mpg drop. It's getting harder, but I'm still able to find stations that run no-ethanol fuel.

Have a good one,
Mike

my average is 19.4 mpg with an A4 with a stall, and I'm on it often. when I baby the loud pedal, it only goes up to 21 mpg. not enough to make me ssssllllllooooowwwww doooowwwwnnnn. (remember that taxi episode when jim is taking his driving test and alex was trying to give him the answer to "what does a yellow light mean?"....sorry, just remembered that...)
which is still way better than the 12mpg my '71 463 powered Trans Am got! and the 19.4 is with the air on.

Around town if I want to conserve gas I shift at 2000 or a few hundred less put it in 5th about 30mph then 6th at 45-50 A/C off around town I get 26MPG and I use cruise control in 6th the car has no problem cruising at 1100RPM.

"BTW, if you run 10% ethanol fuel you'll see about a 2-3 mpg drop. It's getting harder, but I'm still able to find stations that run no-ethanol fuel."

Exactly. I still can find normal gas but all the discount stations are running corn liquor. The car runs well on it but the MPG does suffer. So I decided the discount ain't worth it for the 3 cents I save.

I contribute my 22.4 city and 31.3 hiway to my performance hood seal:leaving: , or my 2.73 gears and 6th gear. These numbers are by calculator from the debit card receipts not the vehicle computer. I do like to use the Instant fuel millage feature though like a vacuum gauge. I try to keep the number as high as possible when on the hiway no matter what speed I'm at.

Concerning the modified cars with larger injectors and a tune, if your tuner didn't rescale the tables used in mpg readings to reflect the larger injectors, you will get falsely high mpg figures on the DIC. Only way to check is to calculate gas in, miles out, the old-fashioned way.
Ed

I never go by the DIC. I have done a comparison over my last couple fill ups and it is always 2-3 mpg too generous. So now knowing that I subtract about 2.5 from what the DIC says and it seems to be pretty accurate.

1998 MN6 Stock

Around town/city = 18 mpg

Drive to work = 22.5 mpg

Flat Highway (Best) = 32+ mpg

Note: OEM Runflats (which I use) will get you 10% 0r 3 mpg better (than non-runflats) due to their stiffness and less rolling friction.

http://i30.photobucket.com/albums/c3...7/DSC00002.jpg
Says it all.

At night Arizona desert I get about 20. But I used to get 17 till replaced the pop-up headlights with flush ones.

With my wife in the car I drive like a woosie and get almost 32 on the highway. For reference my Honda Civic gets 30 in town and 38 highway.

When I first got my 2000 5 years ago I drove to Atlantic city from Ottawa ,once we got in front of our hotel the average was 31 mg. My buddy who droved a VW ..."somethig" could not beleive this .
Then I realised that that milage was based on US gallons and based on the old Canadian gallon that would have been 35-36 mpg...unbelivable. :thumbs:

I was reading up on the 10% ethanol gas that we are seeing in Dallas now, and discovered something interesting.
Someone said the ethanol is about 103 octane in pure form.
So, adding it to regular 87 octane should increase the octane a bit (unless of course they start with 85 octane gasoline or something).

I tried the 10% "regular" from Kroger in my old Mercedes, and it runs like a champ; absolutely no pinging. And it actually starts and idles better when hot.

Course, I just pull up to the Chevron 93 pump in the Vette.
Then, on the way home I get somewhere between 8 and 28 MPG, depending on how I drive (mostly 8, HeHe).

DG

Just a curious question.

Are you resetting the DIC when you fill up?

Maybe you are getting residual MPG's left over from previous miles and is will take some time for it to catch up.

Hmmm... after my long tubes and tune, I seem to be getting really crappy gas mileage. I used to avg. 19.5 with a mixed 70/30 city/hwy driving.

Granted now my driving cycle has flipped, it's mostly city driving and the mileage is piss poor- I am getting an avg of 15 mpg with a 90/10 city/hwy. I think I am driving a little more aggressively so that I can hear the LG Pros sing tho'

Realistically, I don't see myself hypermiling in my '03 Z06... I wasn't too concerned about it but now reading what you guys are getting it's making me wonder.