Originally Posted by Dragoneye
Have you ever driven a vehicle with cylinder deactivation? (just curious)
5-10% actually adds up pretty quick, and when you're on the highway cruising for a while, fuel savings are even greater than GM's estimates.
This statement confuses me:
"How much more fuel efficient would this cylinder deactivating engine be over using all four cylinders?"
Do you mean how much more fuel efficient it would be versus a non-AFM V8?
Secondly, it probably won't activate when driving around a parking lot. Check out that video floating around here somewhere with the G8's AFM engaging. Note that at lower speeds, AFM is off, and all 8 cylinders are firing to keep the thing spinning.
My main gripe about all this boils down to how loud the v8 should sound. The rumble the car makes when you turn the ignition. Japanese cars engines don't vibrate and they whine instead of growl. American cars do. If you are worried about mileage, get a V6 in my opinion.