Could be possible it if one is on more flatter areas with consistent speeds, light loaded, etc. But not on rolling hill rural roads and city operations. My 2013 1500 5.3 had AFM. It rarely ever actually went into that mode. I later disabled it via software, and the difference in mpg over time was not noticeable. AFM just seems to add complexity without a benefit that is comparable to the cost to the consumer in both initial cost and operational cost. Something to appease the government bureaucrats.
And in terms of what the HD pickups main target market is for... commercial, equipment downtime cost money also. AFM in a 6.6 motor that is put in a vehicle that has a primary market of commercial users. And given what HD pickups are typically doing, AFM would hardly kick in. Not the wisest move any OEM has made. But then, the OEM's have been doing all that can to make autos and pickup trucks appear undesirable for the last decade.
Just one more thing to potentially cause a problem. The more complicated one makes the plumbing, the easier it is to stop up the drain.
The 6.2 is not the wisest choice for commercial users also. Premium fuel is the major one. A motor like the current L96 6.0 offers a wide fuel use from ethanol free regular fuel all the way thru the blends up to E85. A commercial user can select the fuel that offers the lowest cost per mile. The Ecotec 6.2, while it can run on regular in some instances, it does so by the ECM choking the motor down. The Ecotec 6.2 is designed to operate primarily on premium fuel for maximum performance. That is why the 6.2 is absent from most, if not all, 1500 pickups that commercial users purchase. Commercial users as not going to pay the inflated price for premium gasoline. And the HD market that the new 6.6 would go to is primarily a commercial market. Personal users of HD pickups are the minority.
Just take the cost of regular fuel in my area, $1.79 and premium in my area, $2.50, and compare over a year the cost for fuel alone on 50,000 miles a typical commercial pickup truck might travel. Assuming a average of 17 mpg for each, regular would cost the commercial user for one vehicle roughly $5264 for the year, whereas Premium for the same period would cost $7352. Since commercial users typically make transportation choices that get down into pennies per mile on a spread sheet, the Ecotec 6.2 is a terrible choice for a commercial user. And the higher initial cost for the 6.2 was not even considered in this.
