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Who Needs AFM?
Thread Starter
Le Mans Master
Joined: Sep 2012
Posts: 7,146
Likes: 1,940
From: Hagerstown MD
St. Jude Donor '15-'16,'18
Who Needs AFM?
Just returned from a 600 mile round trip from Hagerstown MD to Ocean City MD to attend the big Corvette show. I had my Range on for the entire trip. Most of the miles, about 500, were highway driving 60 - 80 mph. About 100 miles we're cruising around in Ocean City. I averaged 30.6 mpg for the entire trip without ever using V4 mode. I believe this exceeds the advertised highway MPG that I assume includes using V4 mode. So, I ask again who needs AFM? Not me.
Le Mans Master
Joined: Nov 2015
Posts: 7,382
Likes: 3,501
From: Lake Havasu City Arizona
I have never noticed any real measurable difference in my mileage after disabling AFM. At most in a couple of test runs it was about a half a mile per gallon going from Lake Havasu to Las Vegas and back, but that could have been due to wind variations, etc.
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Racer
Joined: Jun 2013
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From: Raleigh NC
Just returned from a 600 mile round trip from Hagerstown MD to Ocean City MD to attend the big Corvette show. I had my Range on for the entire trip. Most of the miles, about 500, were highway driving 60 - 80 mph. About 100 miles we're cruising around in Ocean City. I averaged 30.6 mpg for the entire trip without ever using V4 mode. I believe this exceeds the advertised highway MPG that I assume includes using V4 mode. So, I ask again who needs AFM? Not me.
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Sure as heck can’t complain about that MPG.
Advanced
Joined: Jun 2018
Posts: 78
Likes: 31
From: Jacksonville florida area
I did a recent road trip to key west. Once you hit Largo you fall in line and can only average 45 to 50 on the run to key west. I have a manual and turned on the afm just to play. In 5th gear on dead flat sea level road with the cruise control set to 50 switching the afm off would routinely drop the readout 2 or 3 mpg. I left it on for the trip through the islands and averaged 39 mpg (with a slight tailwind) from key largo to key west. I don't use afm much around town or blasting down the freeway because it is constantly shifting in and out of v4. I was however really impressed with it on the slow drive through the keys.
Last edited by BLACKCREEK; Oct 15, 2018 at 11:10 AM.
Safety Car
Joined: Feb 2016
Posts: 4,980
Likes: 3,826
From: Bainbridge Island WA
Fair enough, but it's pretty good anyway. On a 1000 mile road trip I get about 29 mpg. If I used AFM I'd get about 32 mpg. The difference in cost is about $10.00. If gas mileage is a priority for you you'd get a Prius. Nothing wrong with wanting good mileage, but I doubt anyone says, "I'm getting a Corvette because it gets such good mileage."
Burning Brakes
Joined: Oct 2014
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E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 34,937
Likes: 12,351
From: NE South Carolina
Exactly! In fact folks may not need start/stop but it's coming as GM needs all the help they can get.We'll see what engine is in the C8 but my bet is it will be a turbo small CID for the same GM reason. The current Ford GT is a 3.5 Liter V6 with dual turbo's achieving 647 hp! Not bad!
In fact would love to have the F1 KERS (Kinetic Energy Recovery System.) It weighs about 60 pounds with battery and gives 160 hp for about 10 seconds. Could be used when accelerating from a stop as that is by far the worst mpg. Even in normal street driving it could be used until you reach cruising speed as you would not need 160 hp so double the time should be possible. Then like F1, the electric motor turns into generator to recover some of the braking energy to charge the system.
On average about a 1/3 of the energy that gets to the rear wheels winds up going into braking! The internal combustion engine is very inefficient. Only about 15% of the energy in gasoline gets to the rear wheels!
Last edited by JerryU; Oct 15, 2018 at 05:05 PM.
Race Director
Joined: May 2001
Posts: 15,323
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From: Guelph, Ontario
Nobody really NEEDS AFM, as these engines can still get amazing mileage even without it. However, if the technology is there, why not utilize it? I certainly like the idea of saving a few bucks on gas if I'm on a long highway trip. It's doing no harm to me, I have 8700 trouble free miles on my A8 and I let it go into V4 mode all the time. I know, nobody buys a Corvette for gas mileage, bla bla bla, I've been hearing that same thing for years. But gas is pretty damn expensive up here in Canada, it's often over $1.50 PER LITER for premium gas. So that's over $100 to fill the tank. I already spend over $500 a month on the 3 cars in our household, so any savings I can get, I will take it.
