Cylinder Deactivation Demystified

What the heck is it? You may have heard it mentioned ... hey, you might even have cylinder deactivation on your newer vehicle ... but what does it do? How does it work? General Motors and Chrysler use cylinder deactivation to extend the fuel mileage of their big V6 and V8 engines--Mercedes-Benz and BMW do also. In simplest terms, it allows the engine to shut down half of the cylinders when driving conditions warrant, improving fuel economy.

We got to experience this in action during our recent test drive of the GMC Sierra SLT flex-fuel. GM calls it Active Fuel Management. Yep, right before our eyes, we saw the instant fuel mileage gauge register our heavy or light-footedness. You can too...see the digital fuel economy gauge depicting the cylinder deactivation here, or read the full review of the GMC Sierra SLT flex-fuel or see the entire GMC Sierra photo gallery here.

photo © Scott Gable