[redwhtconv]

We just came back from the Rolex 24hr and took advantage to the 600 mile ride to do a milage comparison between ride settings. A little background. Drove down Tuesday night and Wednesday morning, had the car set in Touring and was a little agresive through the traffic, normal. Checked the gas milage when we arrived and was qiite dissapointed with the 23.6. With my C6 I would gotten at least 26 mpg.
So I decided to break the trip as evenly as possible and use the Ecco, Touring and Sport modes. I did my best not to be agresive and did good unit the end of the trip, while I was in the Sport mode.
Results
Mode Miles Avg Speed. MPG
Ecco 211 72 24.8
Touring 204 74 26.0
Sport 189 77 26.4

We left for the Rolex with a little more than 900 miles on the engine and now have a little more than 2400 miles
Would andbody like to to try to explain this.

Had a great time at the rolex. Saw all of the colors at the coral. The Z06 being shown at the Chevrolet display had the Z07 option and insignia on it so I couldnt say what was Z06 and what was Z07.

 

[zimm888]

Thanks for putting in the work and figuring that out. That is interesting.

Personally, I've totally accepted with all of the V8's I've ever had be it GM or Dodge both with 4 cylinder modes that mileage is still gunna be a bit painful. Gotta pay to play! If it's somewhat important to you definitely don't start tuning and engine work. I wouldn't worry about it unless you're getting under 250 miles a tank or something ridiculous.

Other than that how'd the trip go?

 

[MrG69]

Would andbody like to to try to explain this.

Sure...
The car is designed to and wants to be driven fast!




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[Dasyatis]

Can't explain your results. I did some looking at my mileage over the weekend and managed to get the 50 mile count to a little over 29 mpg and also got the 25 mile counter to a high of 31.5.
Got back into town and promptly got them back down to about 20.
The higher mileage was freeway cruise control in eco mode at about 65 for part and 75 for part. Also had some time in sport mode and some twisties. Mileage dropped accordingly…

I'm waiting for a proper road trip to see what really happens. I think in general upper 20's is very possible is you can just go steady. If you want to hear the exhaust note, well, you know what happens then.

 

[elegant]

All cars take at least 2,500 miles to be fully broken in, most twice or three times that. Perhaps the comparison is of a fully broken in C6 versus a still-tight-engine C7? Have most of my cars getting better and better lineage until about 7,500 miles, after which mileage leveled off.

Have not a clue as to why ECO mode was the worst, unless the motor was progressively loosening up at your trip unfolded? Interesting to see if MPG changes as you drive additional mileage.

 

[jsvette]

Thanks for posting Redwhtconv- 'tis a conundrum RedHot has never seen Eco mode so I don't have a direct comparison. On my trip back from NCM, 1,180 miles in tour setting she got a calculated 27.5 mpg (that included the proper brake in, mountain driving, mostly highway and some route 66 and a few stints once broken in, possibly a bit above the legal limit). At last look my cumulative mileage since day one is 25 mpg over 3000+ miles which includes local runs to the Cars and Coffee, Car Enthusiast Breakfast Club, yes Costco as well as a lot of spirited driving out into the desert. Have used Weather setting in a couple of storms in Texas, mostly Touring, and some Sport and Track. Of course she drops down into V4 as the ECU deems appropriate, but I have never seen the point of putting her in Eco mode.

 

[C7Driver]

This mileage thing will be one of my first priorities when my C7 arrives. I know my current '08 coupe with 6-speed manual gives me 29 MPG on a long highway run. Got 31 MPG with my '01 coupe with 6-speed. These figures are based on a full tank of gas, miles driven and then filling the tank again. The trip computer is always a few MPG higher so I go with the actual fuel used.
I expect the C7, after a proper break-in period, to deliver at least 29 MPG on a highway run, in ECO mode, maybe more. I'll post again once I've had some time in my C7.

 

[redwhtconv]

Going back to Florida at the end of February for a family bash so I can repeat the the test. I'll rerun the test on my way backso I should be close to 3K miles. I started with a light fuel tank in Daytona in Eco mode and tanked up; in Georgia, so I'll adjust my fuel in Orlando so I'll be close to the same when I hit Daytona.

 

[Emmdmd]

I know the gas mileage is important, but I didn't buy the C7 because it's economical. But I know its infuriating when a manufacturer makes a claim and real world doesn't come close. That being said, engine break in may have a lot to do with it. I have a Lexus hybrid and was beyond livid at first with my gas mileage. After breaking in the motor, the fuel economy went up substantially.

 

[Redc7]

I see the problem:

Mode Miles Avg Speed. MPG
Ecco 211 72 24.8
Touring 204 74 26.0
Sport 189 77 26.4

It's your average speed, when these cars go thru mpg testing trust me there not driving them at 70+ mph. I saw this same thing with my ATS caddy, wasn't getting the mileage they promise. Why because I too drove like you should.

So here's the test, get on a long stretch of highway again and set your cruise to 60mph and watch your gas mileage. I'll bet you right now you'll see a 4 - 6 mpg improvement.

 

[NightSon]

I'm not sure if this is relevant, but I've noticed a lack of MPG during winter months due to fuel quality. Not sure if it's this way all over the US or not, but here in Missouri the amount of ethanol on winter gasoline seems higher and it directly corresponds to MPG in any of my vehicles. That, plus it may also have something to do with how metal contracts during cold temperatures and expands during hot temperatures. So if the engine is cold, it probably has to work significantly harder (using more fuel) until it reaches normal operating temperature.