My work truck have the cylinder deactivation thing on it. Its an 08 Chevy 1/2 ton z71. My previous truck was an 04 z71 with the 5.3. I have not seen any better mileage with the 08 and I think the 04 would kick its behind in a race. I bought it because the other one had almost 150,000 miles ( tho it never had a problem) but when you are self employed, warranty on a vehicle is a good thing and its a write off as well.