This issue bothered me on my 2012 Ram, too. Why, if it makes sense to turn off 4 cylinders to save fuel when cruising, did the engineers not design these systems to use V4 mode when stopped and idling? My girl's BMW can shut the engine off completely when stopped in traffic and restart instantly as soon as I lift my foot off the brake. Could this be something Chevy can add with a simple software update? Makes no sense to have all 8 cylinders sucking fuel when stopped. Thoughts?

 

I don't think you'd want Chevrolet to be jacking with anything like that, they have enough electrical issues.

 

Cadillac used to have a similar system

 

stop/start systems are obviously a different system than multiple displacment systems.

chevy does have stop/start vehicles...they required a special starter and battery to handle the severe use of constant stop/starts. they also require other modifications; to many to list here....the vehicle has to be built with it...you can't add it. It provides 4% fuel savings

cylinder deactivation systems...makes no sense to shut it off at idle....your fuel consumption is low at idle, you will need 8 cylinders to drive away from a stop...it would take time to make the 4 to 8 cylinder transition.

 

Excellent response, I would also add that some have even wondered why the switch from 4 to 8 isn't even more delayed ( with fuel savings in mind) and it is because of performance, you just don't want that lag, the throttle by wire is already laggy enough...

 

I suspect a 4 cylinder idle would be pretty rough.

The torque management contributes to most of the lag coming off the line.

The Cadillac 4-6-8 system they had back in the 80s was a mechanical nightmare that makes the AFM look polished.