Fuel Smart - Aftermarket cylinder deactivation module?

[Spider-One]

Funny, just saw this today for the first time on Two Guys Garage, coincidence???

 

[Wheela]

hey kaiser, chevy's AFM (active fuel management) actually gives a whopping 8% more fuel econ, I had a 2008 sileverado with a 5.3 4speed 3.73 and it was actually pretty nice, with my flowmasters you could really tell when it kicked in(hear lol), but with the newer models like my 2010 with the 5.3 6speed 3.08 it is never activated. When used in the right gearing it amazing but chevy dont care, they will throw it into anything.

 

[MikeD]

I had a similar system in my 2011 Grand Cherokee "Hemi" and it didn't help at all, I actually get the same mpg in my Raptor while having much more fun.

 

[Deinonychus]

Prior to the motor upgrade in my 2005 Dodge Magnum RT, it had a 5.7L Hemi with MDS (ran on either 4 or 8 cylinders), it got about 24 mpg on the highway.
I also had a 2009 Challenger R/T (which I traded in for my Raptor), which also had a 5.7L Hemi, only because it was a manual shift it did not have MDS. It got 26 mpg on the highway.

So, from the above you might conclude that MDS hurt economy. But that's not the whole story. The final gearing on the Challenger was higher than the Magnum.
At 70 mph: Challenger was 1600 rpm; Magnum was 2100 rpm.

The gearing was most probably the significant difference (but I should include that the Challenger had VVT)

Bottom Line: IMO the Chrysler MDS is not a help for economy of a vehicle in excess of 4000 lbs at speeds above 65 mph.

I would tend to believe that a 6000 lb+, poorly aerodynamically designed vehicle would need to be travelling less tha 55 mph to get any benefit from running on fewer cylinders.