[Z06] Very Dissapointing Mileage
Le Mans Master
Joined: Mar 2002
Posts: 5,955
Likes: 161
From: PNW
No, it doesn't work that way. The mileage calculator doesn't look at the quantity in the tank at all. It just uses the odometer and the amount of fuel released through the injectors. Both are known to the computer so it's a simple caculation. If it really tried to rely on the fuel tank float, it would be soo inacurate it would be rediculous.
... but the DIC MPG indicator still needs to be reset at every fill-up if you really wan't to have an accurate average MPG between fill-ups.
Advanced
Joined: Jul 2008
Posts: 50
Likes: 1
From: Union KY
I have driven my totally stock Z06 from Colorado Springs to Michigan and while averaging 73.8 MPH (cruise at 80 all most the whole way) according to the DIC I averaged 27.7MPG, and according to my calculations 27.2 so I don't think his bad fuel economy was due to his speed. In 6th the RPMs are still pretty low at that speed. Just my .02
Burning Brakes
Joined: Apr 2001
Posts: 860
Likes: 0
From: Austin TX
St. Jude Donor '14-'15
Maybe and maybe not. I found I got 28 mpg on my 2002 Z06 when running cross country between and 80 and 100 while the mileage drops to 23 at 65. Depends where in the rpm range the engine is most fuel efficient. Of course drag increases at higher speed.
Team Owner
Joined: Aug 2007
Posts: 136,140
Likes: 2,433
From: I live my life by 2 rules. 1) Never share everything you know. 2)
St. Jude Donor '11-'12-'13, '16-'17-'18
FWIW, my wife's C4 was getting really crummy gas mileage (it used to get 20 - 22 around town and over 24 highway) and it suddenly dropped to 16 or so around town and maybe 19 highway. Turned out to be a bad O2 sensors (there are 2 on her '95) that was causing the computer to really richen up the mixture.
New sensors and her mileage is back up to where it should be
New sensors and her mileage is back up to where it should be
Melting Slicks
Joined: Dec 2006
Posts: 2,308
Likes: 104
From: Orange County California
I bought my 02 Z06 with 7000 miles on it in 03, and the guy had a Halltech CAI. I've cleaned the filter diligently, but it continued to throw "check engine" lights every other tank of gas. The dealer had no idea what to do. I thought it was adjusting to a lower quality gas, so I started avoiding that station. Bigger problem was it just didn't have the get-up-and-go it should've. It had already-going-go just fine, but off the line? Nope. FIVE YEARS LATER good ol' Corvette Mike found my engine running rich (heck I still got 26-28 mpg in full cruise on the highway), and we put my stock air cleaner back on. The car sails, now, even off the line, with no codes so far. I'm considering a Vararam or K&N, but frankly, I just don't want any other problems anymore. My suggestion is also to switch back and see what happens.
Drifting
Joined: May 2007
Posts: 1,515
Likes: 14
From: Gig Harbor WA
Cruising at 80mph, occasionally downshifting to pass at 80% throttle you say? Before you make any changes to the car, maybe you should try driving the speed limit, practice patience with others on the road, and tread lightly on the gas pedal. At 80 and above, you're punching through a lot of air -- despite the Vette being slippery. You should also check to see if you have any debris in front of your radiator cutting off air flow, and also check your air filter to be sure it's immaculate. If you bought the car used, it's possible a previous owner installed a lower ratio rear end, and that also kills gas mileage. (For comparison, we drove our stock automatic 02 coupe from Seattle, WA, to Carmel, CA, and back mostly at or 5mph above posted speed limits and achieved 31.6mpg using both the DIC and pencil and paper methods. 
Instructor
Joined: Jan 2009
Posts: 184
Likes: 1
From: Providence Forge Virginia
My 'o1 drops from 29 and change at 55-60 mph down to 24 and change if I run the same trip at 70-75 mph. Using the cruise control usually costs me about 2 mpg. I support the " everything is probably fine and leave it alone recommendation". After 50 yrs of competetive driving/car building I still find it tough to leave well enough alone and the if it ain't broke..... mabye its a virus thats going around and we all have been in contact with ?
