The new GM 4.3 V6 has cylinder shut off...can't remember where I read about it.
I did mention it in my thread about keeping the V6 for the 6th gen, (
http://www.camaro5.com/forums/showthread.php?t=277052 ) as it could have the potential to get great mpgs if they were to use it in the next gen Camaro, and make awesome power. I'm not saying they should use it, or that it is my # 1 choice for a V6 engine in the next gen, but there is possibilities for sure.
GM claims a big V8 can be more efficent than a smaller engine or a turbo 6....so maybe a big V6 with cylinder shut off can do the same as compared to a smaller V6 or a turbo 4.