sccaracer46

This week I had an opportunity to make 300 mile round trip driving on I-95 between Datona and Jacksonville FL. This road is level, so I did some testing. I used the "last 25 mile average" setting to record my best segment & the average of all segments driven. I compared driving 70 mph, 7th gear in Track-mode and 70 mph in Eco-mode.
Result: Eco: 34.6 mpg Trk: 32.4mpg A 6.8% improvement in Eco-mode.

Today, coming back I performed the same test in Eco-mode @ 60 mph and the results were amazing!

Eco: Best segment 41.5 mpg! Average of all 25 mile segments, 40.5 mpg.

While, I really don't like driving 60 mph, it does make a statement for being very fuel efficient. But, even cruising at 70 mph, it turns in super mileage! I definitely will use the Eco-mode on long trips. The car moves in and out of Eco-mode seamlessly. I could not tell when it switched unless I was under 60 mph, then you could sense some vibration.

I have a 3LT Non-Z51 7 speed manual.

stic5

Amazing. That's great info. Thanks!

C7 BOB

Which would you rather do?

A - drive a Prius FAST and get 40 MPG

B - drive a C7 SLOW and get 40 MPG



HMMMMMM..........




B

DanTheFireman

I LOVE THIS FORUM! You guys are great, always have the right answer.

DocHolliday

These are incredible numbers...really. I need to try this myself; I cant seem to get away from Sport mode.

Daekwan06

Pretty much sums it up!

Why would you not use ECO mode when just cruising around.

SCM_Crash

Great results...

I bet the results will get better as you break in the car further. Get about 2-3K miles on it and try it to see what happens.

Daekwan06

Good point.. engine & drivetrain still has yet to truly break-in.

sccaracer46

You will find that when in ECO mode at low speeds it stays in V-8 mode most of the time. Also at slower speeds when it goes to V-4 mode I could "sense" the vibration which is annoying. Eco-Mode works best at highway speeds.

When driving around town, I love Track Mode and get around 17 mpg...............that's called FUN! Love to mash that throttle!

Vetteman Jack

That is an amazing MPG number you got. And I thought the C5 and C6 turned in good gas mileage.

mjw930

You owe me a new iPad, I spit my morning coffee all over mine when I read this.

BAD2000TA

Regarding the fuel mileage figures, are these only from the onboard computer or are you also getting the same figures when you're actually filling up the gas tank? Just trying to gauge actual fuel mileage vs. the computer. Thanks.

mjw930

From the computer, using the 25 mile averaging function. BTW the computer is reporting actual fuel mileage. Using fill ups is actually an estimate since you don't have nearly the accuracy the OBC provides but I understand where you're coming from.

slief

Wow.. 41MPG in Eco at 60MPH.. That is truly impressive! Thanks for sharing your results. No doubt, I will take advantage of Eco mode on longer trips and probably my local highway runs. I like saving gas and money and 40MPG is nothing to scoff at. Those are downright incredible numbers from a 460HP sports car. I think Chevy raised the bar in a BIG BIG way when it comes to performance vs. economy.

I know many of you could care less about the fuel efficiency of the Corvette and are even opposed to cylinder deactivation but there are many of us that do care about fuel efficiency and I have to say that is nothing short of amazing and no doubt I will embrace it on an as needed basis.


That is 30% better milage than my wifes 2013 BMW X3 with a 4 cylinder engine!!!!!

460HP + 40MPG = bragging rights!

676911vettes

Were you on 93 octane ethanol and can you get 93 straight gasoline where you are? Straight gasoline in my C6 GS gets about 1.6 to 1.8 better mpg.

Reciprocal

I disagree. The computer doesn't know how much fuel is being burned accurately because it's estimating the amount of fuel left in the tank. The only reliable way is to start with a full tank and record the gallons it took to replace it at the next fill up, best over several tanks in the way you actually drive the car. I bet it comes out no better than the epa number for combined driving.

Paulchristian

Honestly, it sickens me when the corvette gets trashed for having "old school" pushrods, as if that somehow makes it less of an engineering achievement.

Gas mileage has been unbelievable on corvettes since the C5 and improved further with the C7...but team corvette hasn't and probably won't get any real credit for it once the buzz fades on the C7. I place part of the fault on GM for not properly marketing this. To me, this is THE most impressive engineering achievement and they need to bring it to the forefront.

I drove 900 miles to Florida a few months ago in my 4-banger boring as can be Nissan Altima at 65 MPH (average) and got 37 MPG.

adamsocb

I think it is a bit more complicated than that. Since the introduction of sequential fuel injection, the Engine Control Module (ECM) keeps track of the number and duration of the injector pulses and calculates the fuel burned in real time. Some cars may also have a fuel flow sensor. This can be verified by connecting an OBDII/ELM327 data reader to the cars diagnostic port; there will be several fuel burned metrics available. The fuel burned measurement is then combined with the measured distance traveled to calculate MPG.

Example:
The ECM measures a fuel burn rate of 126.18 cc/minute (two gallons per hour) and the car is traveling 60 MPH, the instant MPG will be 30.

As you can see the calculated MPG has nothing to do with the amount of fuel in the tank.

I agree it may not ultimately be exactly right because the ECM has to add up thousands of very small measurements to calculate MPG and a very small error will cause it to be off by 5-10%. My C5 would typically display an ECU calculated 30-35 MPG average on highway trips vs. a gallons to fill-up/miles number of 27-31.5 MPG. Once I established it was constantly 10% off I adjusted accordingly.

I never bothered to make the comparison on my C6 so I don't know if it is more accurate or not.

rgamache

I beg to differ. The mass flow sensor knows very accurately the airflow and the oxygen sensor gives the mixture... So the fuel usage is accurately known. I have found good agreement between the traditional method of fillup and miles traveled to the computer generated average mileage.

robvuk

The mileages is NOT calculated by remaining fuel in the tank! The fuel is metered at all times. Discrepancies can only result from a clogged air filter or tire diameters that are not stock.