There hasn't been any word yet if it's just an option, or if it's a function that can't be avoided like the current Impala SS.

I know how it works and that it doesn't affect performance, I'm just worried about long term wear & tear on the engine. Such worries as cylinders wearing unevenly, or worse yet, will it get stuck in 4cyl mode after 100k miles? Just something I don't want to risk if I'm going to spend 40k on a car.

First off, the engine wear will be the same. The piston doesn't stop moving.
Second, if all else fails, the car goes into full V8 mode, and cannot get stuck in 4 mode.
Can you avoid it? I dont think GM wants you to. AFM could get the 6spd autos out of any type of gas guzzler tax, much like the manual trans skip shift feature.

I still want a switch AFM ON/AUTO/OFF that gives the driver control.
Auto is how it is originally shipped.
ON makes the engine run in 4 cylinder mode all the time.
OFF makes it fire on all cylinders.

I think I see the reasoning behind this. If I were to want to putt around town and conserve fuel, then I could leave it in 4cyl mode. If I wanted to run harder, I could put it back in auto.

HOWEVER....if this car weighs what we think it will, or even in the 3700 pound range, the gas mileage would suck in stop/go driving. Too small an engine would have as adverse effect on mileage as too much engine.

If such a switch was included it would only have Auto/Off modes. This being because i don't believe it can idle correctly @ 4 cylinder mode, as well as to keep idiots from complaining about not getting 4 cylinder gas mileage while putting up with the crappy performance of the 4 cylinder running of a V8 engine.

Still doesn't exactly answer my question. Does anyone have a high mileage vehicle with an AFM equipped V8? I want to know how it wears or if it is any more problematic than the norm of running on all 8 cyl.

There are probably some high mileage ones out there somewhere.

Like Big Al said, the pistons don't stop moving, though the valves do. I really can't see where AFM would cause any more wear than normal use.

A failure in the AFM management is probably no more or less likely than a failure in any of the other hundreds of electronic functions going on at any one time in a modern automobile.

I think the only way to avoid AFM will be to get the manual.

It does have a switch. Its in front of the driver, to the right of the brake pedal.

Stay out of it, it will be in 4cyl mode.
Talk to anyone that has driven a Impala SS, LaX Super, any Silverado with a 5.3. So far, I have heard zero problems. Again...if it fails, it fails into V8 only mode. It has to turn ON to shut down the lifters. If it never turns on or if the sensor fails, it wont stop the oil from going to the lifters.


I do wonder if the LS3 will be available at an extra cost option for Autos, on top of the fact that the car could see a gas guzzler tax.

Alright, I think I got it now. This is all good because I was originally planning on getting a manual transmission anyway. And thanks for the info on how AFM works, GM really doesn't explain it all that well. Hence my confusion.