WHy did GM spend so much money designing its Active fuel management program to save gas while cruising and not use it in more models?
Since seeing it was left off of he LS3 in the corvette, i've been thinking. Dod has been around since 2005, on the 5.3/Ls4 engines. Used in the impala ss, gp gxp, and a few suv's.
Does anyone else think GM should be using this technology more widespread in order to increase Highway mpg over a variety of models?

The same as GM's other hybrid system showing up in some trucks/suvs. GM needs to combine the technology and filter it down to cars to farther boost mpg.

If active fuel management increases mpg on the ls3 by only 15%, that would boost the corvette to over 34+mpg. Making the corvette more fuel efficient then todays impalas and malibus.

 

GM is using the AFM to bump up mileage where it needs it to meet CAFE. They don't use it on every model so that when CAFE numbers need to change they can impliment it on new models, also it costs more money to make than a non AFM engine b/c of more parts and labor to assemble.

 

Plus there are concerns that AFM in their true performance cars will cause exhaust systems to sound quite terrible running in 4-cylinder mode.

 

Is GM reallly concerned about that though? Also, it idles as a V8... I can't imagine really hearing it at cruise unless you put some loud exhaust on it, in which case you can mod the programming so AFM doesn't come on.

 

I'm sorta wondering why it's not used in more 6 cylinders. I'm not sure of any GM models out right now that have it (v6 wise)

 

I have been wondering this myself. I believe Honda does it on some of their V6s.

 

The 3900 v6 in the Impala has AFM.

 

I floated that idea over on Corvetteforum, and they all had a hissy fit. Apparently their mindset is that they need all 400 horses when they're on the brakes slowing down for a red light.

 

http://www.gm.com/company/gmability/...od_050803.html

The Epsilon 3.9s have DOD along w/ the 3.9 in the Impala, the 3.5 doesn't to my knowledge. The 3400 is to old to have DOD. The HF engines would be a totally different game.

 

The w-body 3.9 is the only one with AFM.

 

My bad I knew the EP 3.9 had VVT so I assumed it also had AFM.

 

this technology could even be put on 4 cylinder engines

 

It would be nice if it did have AFM. I don't get the greatest fuel mileage.

 

I can understand them not using it on every model level of engine and the added costs. Also, I was not even aware of it being used on 3.9 impalas. Does anyone know what mpg the 3900 impalas are rated at?
The exaust sound is a good point about Gm staying away from this technology in high performance cars.
I would just like GM to start using some of the fuel savings technology in cars instead of keeping it for suv's and trucks.

Is AFM on any vehicles with a 5 or 6 speed? I could see more benifit their being able to hold the car at a cruise speed then the automatics GM currently has.

 

For Honda, I think it's currently only used on the Odyssey minivans (and only the "Touring" model), and the Accord Hybrid. Maybe the Pilot? I don't know. I do know the standard Accords don't have it, and none of Acura's line uses it.

I do wonder why it hasn't been ramped up faster. Perhaps not delivering the hoped-for fuel economy gains?