What's the best gas MPG you have had?

Best I ever got was 29.3 by the computer.  This was going through several passes on I-5 with the cruise set at 70.  Once I got to my destination I ruined it by having a little fun on a back road!

2008 Coupe LS-3  Corsa Extreme Exhaust with Crossover pipe and Vararam Intake System.

I have a 2005 6 speed coupe and the best overall mileage I  racked up on a 800 mile Interstate run was 27.5 when it was four months old. I have not been on any long  trips since.

Greatest per mile gallon figure for a tank: 26.879 (6/11/08) Greatest distance on a tank: 421.0 miles (11/13/2009; 15.918 gallons; 26.448 mpg)

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Tom Stoner

i bought a 2006 coupe with 12000 miles, gas milage best number so far is 21.6mpg on the highway "65mph" the car now has 13300 and 21.6mpg is tops.  do you think something might be wrong with this car? i am the second owner and thought i would be getting much better gas milies right out the gate. any ideas, comments are very welcomed

thanks,
anthony

You fuel injectors may be clogged. Try running Chevron with Techron gasoline and additionally adding some Chevron Techron/Fuel Injecter Cleaner  to your tank. Costco sells it at a discount. I had a 86 that had one injecter completly clogged and that opened it up. Since then I only run Chevron or Shell (has additive). Presently I have a 2001 convert, a 2005 convert both with the Z51 (lower rear end gear ratio) and a 2010 Grand Sport convert. The first two see 25 - 27 mpg but the GS does not do as good, maybe due to the wider body and tires. I bought it in Texas and brought it to CA. At the beginning of the trip I was getting 20 and at the end 23. I was doing 80 mph where I could driving the speed limit plus 5 mph.

Picked up my 07 in Carol Stream Illinois and headed back to North Dakota. Maintained 5mph above the limit all the way to Fargo and got 28.3 mpg with a minimum amount of playing. Once inside North Dakota I played a lot and got 27.5 mpg!

I consistently get 25/26 mpg on my '05 Convertible running between 70-75 mph.  Most folks are amazed at the gas mileage!

Whether you have a manual or automatic transmission also makes a difference.
With the type of driving that I do here on Long Island, I noticed about a 2 to 2.5 mpg difference between my '07 with an automatic transmission and the '08 with the manual transmission (25mpg to over 27 mpg). Other differences are that the '07 had the LS2 engine, and the '08 has the LS3 with the  Z51 manual transmission which has the taller gear ratios (about 10 to 14 percent) in the first four gears.

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2008 C6 Coupe, LS3, Blk/Blk, 6M Z51, 3LT

thanks everyone..

Out on the road, cruise set at 70MPH I get between 30-32 MPG instant, and about 27 MPG average.  In the city, the average drops down to 21 MPG, but then I like to floor it as soon as a light turns green, and accelerate to the posted speed limit for that road.

Hi, anthonym2010-04-17 06:39:20

Anthony:  Miles should not be a factor.  My '07 has 25,000 and is now getting the best mileage per gallon ever.  What does your onboard computer show when you are driving, such as the instant fuel economy?  What engine and transmission do you have, and how do you normally drive it?  I have the regular 6.0 liter 400 hp engine with an automatic 6 speed paddle shifter.  I have modified the exhaust (Magnaflows) and have a BBK cold air intake.  I have not changed the air mass meter.  As I said, in the city I get about 18 to 20 mph, but a good 30 to 32 on the open road.  The best setting I have found is cruise control set at 70 in the open highway.

Well it looks like we all have about the same mpg. I also get  about 30-32 at 70mph on highway and have gotten as good as 21.5mpg in town,(not very often).

I have a 2007 Z51 with automatic. K&N cold air kit and throttle body spacer are my old real mods here. Always 22-23 MPG in the city and 31-33 MPG highway (regular gas, no premium here)

I run Royal Purple synthetic oil always, which I know really helps but I truly believe that the K&N cold air kit with the throttle body spacer are helping it breathe here. Remember that an engine is nothing more that an a big air pump, so if you can make it better to inhale and exhale, you are making it more efficient.

CPAL1843.

CPAL1843,

Best prices were both on Amazon.com, believe it or not!

Throttle Body Spacer is $59.00 (free shipping) - http://www.amazon.com/2005-2007-Corvette-LS-2-Throttle-Spacer/dp/B000JLGFFY/ref=sr_1_1?ie=UTF8&s=automotive&qid=1272396633&sr=1-1

I drive an 08 Atomic Orange Metallic coupe, totally stock, about 25000 miles on it.  It is a daily driver, plus some autocross and drag racing.  I get 19 in town, 29 to 30 on freeway trips.  This is based on ACTUAL MEASUREMENT and calculation, and NOT on the dash display.  The calculation in dash display always measures higher than it really is, by 1 to 2 mpg.  This was also true with my C4 and C5.  I'm not sure whether it is set this way to make you think it is better than it really is, or whether it has something to do with the way the fuel metering gauges work.

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Every time I fill up, I write the odometer reading on the receipt. Then I enter this and  the date, total cost and number of gallons on an Excel spreadsheet for a record on a yearly basis. This gives an accurate mpg,  and you can also extrapolate to get some other interesting information, e.g. cost/mile, miles/day, cumulative mpg and miles per day; and projected yearly figures like total miles, gallons and cost. And if your driving habits are like most people and you plot the number of days between fill ups vs. mpg between fill ups, you'll see the inverse correlation between the two.
You'll also be able to show the wife or husband, how your driving habits produce a better mpg than theirs!



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2008 C6 Coupe, LS3, Blk/Blk, 6M Z51, 3LT

Frank, you're even more compulsive than me.  

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FrankM: I too use an Excel spreadsheet, and have for all my cars dating back to 1992.  I enter the same information as you and get about the same list of calculated results, so our spredsheet designs must be similar.  Of course if you set this up for one car just once, it's easy to copy the spreadsheet and erase the old data to build records for another car.  Here are the figures for my automatic transmission LS2 '07 convertible with a 2.56:1 axle ratio, updated from what I posted back in January.

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Tom Stoner

To honu and tgstoner:
Honu: My wife uses another descriptive before "compulsive" that begins with an "a". It's been a curse of mine throughout life. But I do remember the VW Westphalia Camper, although my preference for new wheels several years out of school was a '63 Pontiac Catalina convertible.
The spreadsheet with gasoline usage and mpg is pretty interesting, but I find that a separate spreadsheet with the dozen or so maintenance items to be of greater value - things like fluid flushes, air and fuel filters, serpentine belt age, etc. Even though you have all this info with the receipts in your maintenance folder, the spreadsheet allows you to see it all at a glance with notes or items highlighted on maintenance to be performed with the next oil change.

Tgstoner: My figures are about 2 to 2.5 mpg greater than yours because I have the 6-speed manual xmission. I also drive pretty conservatively except when challenged or when I "pick my spots". Even though my Z51 xmission has taller gear ratios in the first four gears, their effect is probably negligible when driving conservatively.  To avoid the 1 - 4 forced shift when driving moderately, I ordered and installed a CAGS bypass the very first week after deliveryof my C06. My driving and shifting enjoyment tripled when I no longer had to worry about being blocked from second gear. It was difficult not to instinctively try to "mash" into second when it was blocked.


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2008 C6 Coupe, LS3, Blk/Blk, 6M Z51, 3LT

I have an '07 Z06 and I've gotten as high as 26 mpg on a cruise to Vegas from the SF Bay Area.  On the way back... fuel mileage was not a concern.  I was just enjoying the desert vistas at 100+ mph for a good portion of the drive.    However I have seen the instant reading hit 40 mph a few times.  Around town I generally get about 17-19 mpg depending on whether or not I've spent any time in traffic. 

Yeah, but the instant mpg doesn't mean beans.  I've seen it run at 99 for a while when coasting down a long hill.  Apparently it won't go to triple digits.  Of course if I'm going hard up the same hill, it'll say 8 to 10 at best.  And then there's the instant on the drag strip.  :-)

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The car computer is instaneous mpg and does not truely represent mileage.

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Stephen P

Here is an update to the figures I posted back in January, 2010.  We took the car on two 8-day trips in July, 2010, for a total of more than 6,500 miles and generally running 5 to 8 miles per hour above the posted limit we were experiencing exceptional economy.  This is a great grand touring car! Greatest distance on a tank: 481.0 miles (7/7/2010; 16.604 gallons; 28.969 mpg)

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Tom Stoner