Miles per gallon
Racer
Joined: Mar 2008
Posts: 321
Likes: 0
From: Grandview Texas
My current car, being a Z06 gets 22-23. I drive conservatively for the most part, but I gaurantee you I open'er up enough that Im not getting any valve deposits 
. Now, my old 02 base C5 w/an Auto got about 25-26 avg.
. Now, my old 02 base C5 w/an Auto got about 25-26 avg.
Burning Brakes
Joined: Apr 2009
Posts: 1,163
Likes: 4
From: Concord California
Interesting, I'm averaging 26.5 to 29.4 mpg with street/highway combine. I also have C6 Z06 rims & tires (wider) so I should be dropping in mpgs than what I'm getting. I tend to drive light but love the fact that I can punch it when I need the V8 power to get me out of a snag. I once got an average of 32.2 mpg but that was a long freeway driving on flat highways so I don't claim that as my average. My average is going to work/freeway/city streets and that is what I feel is my C5's average.. Still good for a sporty muscle vehicle, top that Euro sports cars costing thousands more...
Melting Slicks
Joined: Sep 2010
Posts: 2,208
Likes: 6
From: Prince George VA
I got a new LS6 with intake and full exhaust, tuned. I average 18.1 miles a tank. The DIC says anywhere from 18.0-18.8. So it's pretty close. I do try to drive normal but sometimes I can't help but to mash the gas pedal. Nothing but a highway cruise around 70-75mph I average 27mpg.
Whish is funny because my last car was a turbo'd 4 banger and averaged 19mpg.
Whish is funny because my last car was a turbo'd 4 banger and averaged 19mpg.
Le Mans Master
Joined: Feb 2007
Posts: 9,294
Likes: 1,527
From: Oviedo Florida
2024 C5 of the Year Finalist - Modified
2024 C2 of the Year Finalist - Modified
2023 C2 of the Year Finalist - Modified
2021 C2 of the Year Finalist - Modified
2016 C5 of Year Finalist
24 miles per gal.-700hp.
Safety Car
Joined: Sep 2005
Posts: 4,060
Likes: 101
From: Southeast, Tennessee
St. Jude Donor '09 thru '26
i average 23-24 mpg on a 50/50 highway to local "in town" commute whenever i decide to drive the vette to work (which is rarely). when i travel with it, a/c blowing, cruise set at 78mph i consistently get just a hair over 30mpg. the best i have ever calculated was 31.2mpg on a trip averaging less than my normal 70+ speeds. i would suggest you double check your math and if you are sure you are accurate, i would make certain that i used the exact same gas station to fill up twice or three time and calculate the numbers based upon when the pump cuts out automatically and not forcing more gas in. if you are still in the 15 range, i would suggest that you bite the bullet and spend a few bucks and give the car a full tune done by a qualified technician who specializes in working on older vettes. if you are unsure who to use, get in touch with the local corvette club and talk to some of the members and see who they suggest using. you should be doing a lot better than you claim to be doing.
Instructor
Joined: Mar 2011
Posts: 235
Likes: 0
2004 A4 and I get about 16-17 city. the gov site says that's what it's supposed to get, and I get about 25mpg on the highway. I don't know how you guys are getting such great gas mileage in the city? I have no bad codes and a clean air filter.
Melting Slicks
Joined: Jan 2004
Posts: 3,012
Likes: 15
From: Jensen Beach FL
2004 M6 with 4:10 gears and Diablo Sport tune 19-21mpg around town. I get 24 hwy. Motor is stock and I have a modified air intake and non run-flats. Run-flats tend to get better mpg. Before the 4:10's and non run-flats I was getting 22-24mpg around town 30 hwy.
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Racer
Joined: Mar 2010
Posts: 465
Likes: 72
From: Discovery Bay, Ca.
Yeah, what he said. I just got 377miles on 16.1 gallons of gas which equals 23.41mpg. 377/16.1=23.41. This was the first time I'ver ever put more than $70 in a car's gas tank. Motorhome, we'll that's a different story. This calculation takes into account my all around driving experience with a little heavy foot every once in a while at 5mph over most of the time. On the freeway, driving like I have a egg under my foot or, with cruise control on at 68mph; I'm getting 29.9mpg on long runs.* Haven't been able to break that 30mpg mark for a whole tank yet although if someone asks I'll tell them she gets about 30mpg on the freeway. I have seen the DIC post over 38mpg on long downhill streches though. ;-)* Haven't done a long distance check since I gave her a tune up with Iradium Plugs and new hi performance wires. I'm hoping that will do the trick! Next thing to do would be to increase the air pressure past the 33psi that I normally run in the tires. Not to mention my steering was dragging a little and now that is fixed which should yeild higher mpg's as well. Oh, Oh and the Zaino was that I just did... That's got to be good for a couple mpg's and 50HP. LOL !!!
Last edited by Mecinoid; Apr 10, 2012 at 10:25 PM.
Thread Starter
Drifting
Joined: Jul 2011
Posts: 1,509
Likes: 10
From: Bay Point California
Stay tuned. I'm thinking it's just the way we drive. The car seems to be too perfect for it to be the problem here. I love this forum.
Last edited by torchredmadness; Apr 10, 2012 at 11:56 PM. Reason: Want to add comments.
Le Mans Master
Joined: Sep 2007
Posts: 7,604
Likes: 8
From: Belleville Il
Low 20's urban/suburban mix,,close to 30 on trips(and that's NOT puttering at 55
)!! City I tend to skip gears on my owns as traffic precludes "enthusiasm". There are always a few frisky romps on every tank,,ya just CAN'T resist ALL the time!!
)!! City I tend to skip gears on my owns as traffic precludes "enthusiasm". There are always a few frisky romps on every tank,,ya just CAN'T resist ALL the time!!
Tech Contributor
Joined: Dec 2003
Posts: 19,384
Likes: 87
From: Horncastle Lincolnshire, England
2023 C5 of the Year Finalist - Unmodified
Mines a stock A4 with 3.15 rear end
I make about 21 mpg around the local roads in England driving reasonably "spiritedly". If I try for economy I can stretch it to about 25 mpg on a run at about 70 mph. That goes up to about 27/28 if I drop the speed to 40-50 on the way to a show. I normally reset the average at the start of a trip and check at the end.
With gas at $9+ a gallon I probably pay more attention to mpg than most.
I make about 21 mpg around the local roads in England driving reasonably "spiritedly". If I try for economy I can stretch it to about 25 mpg on a run at about 70 mph. That goes up to about 27/28 if I drop the speed to 40-50 on the way to a show. I normally reset the average at the start of a trip and check at the end.
With gas at $9+ a gallon I probably pay more attention to mpg than most.
Racer
Joined: Mar 2010
Posts: 465
Likes: 72
From: Discovery Bay, Ca.
Melting Slicks
Joined: Oct 2004
Posts: 2,730
Likes: 92
From: Lakeland FL
Plot mpg versus trip mph
After 9 years and 100 tanks of gas, my 03Z has averaged 20.5 mpg at an average trip speed of 37.6. Indicated mileage was 21.4 mpg. Your average speed for the tank is the key. Right now, my mpg is roughly half of what the trip/tank mph is, ie 40 mph for tank, 20 mpg.
Long term equation for actual mpg: mpg = (trip/tank mph X 0.3) + 8.9.
So, a highway trip at 60 mpg for the entire tank should yield (60X0.3) + 8.9 or 26.9 mpg. Mpg at very low speeds drops off considerably, I've had a 23 mph tank with only 13 mpg.
Anyway, record your tank mph each time and you'll see the relationship.
Long term equation for actual mpg: mpg = (trip/tank mph X 0.3) + 8.9.
So, a highway trip at 60 mpg for the entire tank should yield (60X0.3) + 8.9 or 26.9 mpg. Mpg at very low speeds drops off considerably, I've had a 23 mph tank with only 13 mpg.
Anyway, record your tank mph each time and you'll see the relationship.
Melting Slicks
Joined: Jan 2009
Posts: 2,127
Likes: 33
From: Easley/Anderson South Carolina
Dang, I def need a new tune. I am getting 12.8-13.5 a tank, been this way for about 9 months.
240/244 .609/.596 111lsa, LT's catless, 60lb injectors, fast 92/90 t/b, Vararam, TF 220's, on an LS2 shorty.
240/244 .609/.596 111lsa, LT's catless, 60lb injectors, fast 92/90 t/b, Vararam, TF 220's, on an LS2 shorty.
Burning Brakes
Joined: May 2004
Posts: 1,201
Likes: 2
From: Frederick Md
I just checked my computer (I keep complete records of everything)on all 6 of my Vettes) and my 98 6sp z51 convertible has car now has 27,043 miles on her clock..
Total average since day one way back in early 99 comes to 24.7 mpg the last 3 tanks average 26.5 ....
My 4 sp 64 365 horse car averages 16.4 over the last 12 years .(I drive it gently lol)
My 72 averages 10.9 over the last 12 years (drive it hard)
My 76 averages 10.8 over the last 12 years (drive this one hard to)
My 79 is an automatic ans is a heavy car only averages 9.4 over the last 12 years (its too slow to drive hard)
My 35th anc (an 88 naturally ) an also an automatic averages 22.6
My old 95 6 sp Z51) which I sold a few years ago (because it was BLACK) averaged 24.4 during the 4 years I owned it I traded it for the 98 when I retired as a present to myself
My old 68 SS396 Chevelle (that I sold in 2003) with dual 4 barrel carbs and a worked over tranny averaged 6.2 mpg ... but that did a lot of 1/4 mile short trips
Bob G.
Total average since day one way back in early 99 comes to 24.7 mpg the last 3 tanks average 26.5 ....
My 4 sp 64 365 horse car averages 16.4 over the last 12 years .(I drive it gently lol)
My 72 averages 10.9 over the last 12 years (drive it hard)
My 76 averages 10.8 over the last 12 years (drive this one hard to)
My 79 is an automatic ans is a heavy car only averages 9.4 over the last 12 years (its too slow to drive hard)
My 35th anc (an 88 naturally ) an also an automatic averages 22.6
My old 95 6 sp Z51) which I sold a few years ago (because it was BLACK) averaged 24.4 during the 4 years I owned it I traded it for the 98 when I retired as a present to myself
My old 68 SS396 Chevelle (that I sold in 2003) with dual 4 barrel carbs and a worked over tranny averaged 6.2 mpg ... but that did a lot of 1/4 mile short trips
Bob G.
Racer
Joined: Mar 2010
Posts: 465
Likes: 72
From: Discovery Bay, Ca.
After 9 years and 100 tanks of gas, my 03Z has averaged 20.5 mpg at an average trip speed of 37.6. Indicated mileage was 21.4 mpg. Your average speed for the tank is the key. Right now, my mpg is roughly half of what the trip/tank mph is, ie 40 mph for tank, 20 mpg.
Long term equation for actual mpg: mpg = (trip/tank mph X 0.3) + 8.9.
So, a highway trip at 60 mpg for the entire tank should yield (60X0.3) + 8.9 or 26.9 mpg. Mpg at very low speeds drops off considerably, I've had a 23 mph tank with only 13 mpg.
Anyway, record your tank mph each time and you'll see the relationship.
Long term equation for actual mpg: mpg = (trip/tank mph X 0.3) + 8.9.
So, a highway trip at 60 mpg for the entire tank should yield (60X0.3) + 8.9 or 26.9 mpg. Mpg at very low speeds drops off considerably, I've had a 23 mph tank with only 13 mpg.
Anyway, record your tank mph each time and you'll see the relationship.
Racer
Joined: Mar 2010
Posts: 465
Likes: 72
From: Discovery Bay, Ca.
With those injector and cam it would be hard to get much better imo. Same goes for me with those injectors and my Supercharged LS1 in the Firebird. IT sucks gas.... as they say... You can literally see the gas gauge move toward empty as I step on the gas. However, I was told at the time I should expect to get improved mileage. Haven't been able to prove that but, I also haven't use ANY restrant when it comes to that car. It's just too hard to keep my foot out of it. I do well in traffic however, give me a mile of open space and I might as well start feeding dollar bills into the gas tank. 