Rebel Yell

First off I need to post a disclaimer: These numbers are not scientific as I'm just too sorry to do that. The numbers are straight from the trip A&B in the DIC. The car is a 2016 base A8 convertible.

We left for our road trip Sunday, leaving Concord, N.C. heading for Lexington, KY. This run was 99.9% interstate, with one 20 minute traffic back-up on I-65. I left the Range V4 disabler off this entire run. The bitch bucked, and shuttered on quite a few occasions when accelerating to pass slower vehicles.

Miles to Lexington, KY - 440 (rounded up)
MPG's - 32.7
Avg. speed 69 mph.

Second run was from Lexington, KY to Tinley Park, IL. The Range was on the entire time. This run was 100% interstate with no traffic back-ups. The old girl was smooth as silk when accelerating to pass slower vehicles.

Miles to Tinley Park, IL - 364
MPG's - 31.6
Avg. speed - 66 mph

So, there it is, 1.1 mpg loss over nearly the same miles driven. Off the top of my old head that's around an 18 miles per tank loss. IMHO that just ain't enough to worry about in the big scheme of things. And, the car ran so much better. It was happy, and I was happy. The Range will be on for the rest of the road trip.

JDSKY

Thanks for posting this up. Non-scientific comparison is close enough for me as I also don't see how the AFM is really going to save that much fuel in real world driving conditions. It is far too aggressive for my tastes and the car is just constantly cycling in and out of modes. Why GM does not offer an option to turn it on and off or simply reserve its use for Eco and/or Touring modes is a complete head scratcher to me. Yes, it is disabled when selecting manual shift mode but paddle shifting a car has never really appealed to me at all.

Ordered mine over the weekend and cannot wait to get the full time V8 sports car I purchased out on the road with it.

Kevin A Jones

Thank you for your effort and certainly scientific enough for me. That's pretty amazing mileage in either case for a car such as the C7.
Also, thanks for taking one for the team in putting up with the V8>V4 for 440 miles. Not something I would have wanted to do.

rmorin1249

Rebel, this corresponds with what I found after receiving my Range. I conducted several similar tests and found differences between 0.8 and 1.8 mpg. I agree it's not enough to convince me that V4 mode is worth using. Not many folks buy a Corvette for mileage and I'm surprised GM insists on using it on a car like Corvette. Even without V4 the car gets incredible mileage for one with a 6.2 L V8. Kinda sad.

KenHorse

Makes a bigger difference with an M7. And while I don't have empirical data to share, I do know that after a couple of years running in ECO mode, I saw an improvement of more than 1 MPG on hwy trips

Yoggi

911Hunter

Good to know. I'm still trying to convince myself of getting the range for my car, but frankly I'm not able to differentiate when my car enters the V4 mode, don't feel the difference while driving on my '14 Z51 A6 automatic transmission, maybe is more notorious on the A8 automatic transmission ('15-...model years)

capeli

Slynky

From what I read here, there is no real need for this add-on if one has an M7, is there? Or have I missed something posted here that makes it useful for both the A8 AND the M7?

dashotgun

I think it would be interesting in around town driving where you might save more gas with the V4 then again not. I leave the range on all the time although I set it up with a switch.

Patman

There is no need for it on the M7 since it'll only go into V4 mode in eco mode, so you just need to drive in any of the other modes.

Flame Red

The whole AFM thing was a huge abortion for GM. They took a fine car and give it major Torque Converter issues, and damaged their brand. I suspect this was to appease the Obomination regulators, after all, he bailed them out. GM should have just done the same as they did with the LS3, and leave it alone.

My unscientific results are very similar. Except I cannot no where near to that 30 MPG mark so many here get. Perhaps I have a lead foot!

JJLAI724

Rebel Yell - do you have a spoiler on your vette? If so what stage spoiler. I have a M7 and the best milieage I've had is 27mpg in ECO mode. Average speed is 77mph. This is calculated via scientific mode.

And to all the other's, I didn't buy a Vette to get good gas mileage, I don't mind putting the pedal to the floor and burning up the gas. It's just fun to do the reverse and see how many miles I can get per a gallon so that I can tell all my hybrid buddies that this 2 seater car is getting as good mileage as their Prius or Volt on the highway.

etaylor14

Thanks Rebel for the post I ordered mine last Friday and am looking forward to using it

Slynky

In anticipation of my car being built, I donwloaded the owners manual but I'm only on page 30...Thanks for the reply.

TEXHAWK0

Last time I drove a Ross Texas, got 32.9 in interstate in 6th gear, no eco mode.

Anything u like

Patman

Maybe GM has been tweaking this system with each additional year of the C7, because on my 2018 it's almost seamless when going in and out of V4 mode and I rarely use the paddles so mine is cycling back and forth quite often every time I drive it. I have 7700 trouble free miles, not a hint of any transmission issues either. I have no problems letting it go into V4 mode when I hardly notice it and it's giving me a nice boost in MPG too (in my testing I get about 5% better MPG on the highway) I see no logical reason to disable this system for me when it's not causing me any harm and is saving me money at the gas pumps (premium gas is about $1.50 per liter here!)

JDSKY

I think it depends on how much you pay attention to what the car is doing if you notice it or not. Maybe it is more obvious in a vert as I can definitely hear it going into v4 mode each time with the top down and can feel the car back off in power. I just want all 8 cylinders on tap at all times. V8 sound and power not V4.

Cowboy26a

I ordered one today for my 16 Z06. I will see if it eliminates the sluggish response when speeding up a slower speeds.