Car care · Elgin Auto Sales & Service Center · Elgin, IL
What Is Cylinder Deactivation?
Some V8 and V6 engines quietly shut off part of the engine when full power is not needed. Here is how cylinder deactivation works and how much fuel it can save, along with other common engine technologies, according to fueleconomy.gov, the U.S. government fuel economy site.
Up to 5%potential efficiency gain, cylinder deactivation
8 or 6 to 4 or 3cylinders working when not all are needed
Up to 8%turbocharging with a smaller engine
3% to 4%variable valve timing and lift
The short answer
Cylinder deactivation "turns off" some of an engine's cylinders when they are not needed. Fueleconomy.gov says it essentially shuts the valves to some cylinders so fuel and air are not pumped into them, temporarily turning an 8- or 6-cylinder engine into a 4- or 3-cylinder engine to save fuel. Its estimated potential efficiency improvement is up to 5%.
How cylinder deactivation works
Fueleconomy.gov says cylinder deactivation "turns off" some of the engine's cylinders when they are not needed by essentially turning off the valves to those cylinders, so fuel and air are not pumped into them. That temporarily turns an 8- or 6-cylinder engine into a 4- or 3-cylinder engine, saving fuel.
Fueleconomy.gov rates the potential efficiency improvement at up to 5%, citing a 2015 National Academy of Sciences study of fuel economy technologies, with most values rounded down to be conservative.
From Advanced Engine Technologies (fueleconomy.gov), read November 9, 2026.
Other names for cylinder deactivation
Fueleconomy.gov notes that automakers use several names for the same idea. If you see any of these in a vehicle's description, it has cylinder deactivation:
- Multiple displacement
- Displacement on demand
- Active fuel management
- Variable cylinder management
Your owner's manual explains how your engine's system works and whether it needs any particular oil or care.
From Advanced Engine Technologies (fueleconomy.gov), read November 9, 2026.
Cylinder deactivation vs. other engine technologies
Fueleconomy.gov lists these advanced engine technologies and their potential efficiency improvements:
| Technology | What it does | Potential efficiency improvement |
|---|---|---|
| Cylinder deactivation | Turns off some cylinders when they are not needed | Up to 5% |
| Turbocharging with engine downsizing | A compressor forces more air (and fuel) into the cylinders, so a smaller engine can make the power of a bigger one | Up to 8% |
| Variable valve timing and lift | Adjusts when, how long and how far the valves open to suit engine speed | 3% to 4% |
| Gasoline direct injection (GDI) | Injects fuel directly into the cylinder; the cooler mixture allows higher compression or better spark timing | 1% |
From Advanced Engine Technologies (fueleconomy.gov), read November 9, 2026. Estimates come from a 2015 National Academy of Sciences study, most values rounded down; real-world results vary by vehicle.
Many engines combine several of these. For more, see what is a CVT transmission and auto start-stop explained.
Service at Elgin Auto Sales & Service Center
Check engine light on or engine running rough? Schedule service or see our service specials.
Our service department at 1200 E. Chicago St. in Elgin is open Monday to Friday 8 a.m. to 5 p.m. and Saturday 8 a.m. to 4 p.m., and is closed Sunday. Get directions.
Cylinder deactivation FAQ
What is cylinder deactivation?
A technology that turns off some of an engine's cylinders when they are not needed, temporarily making an 8- or 6-cylinder engine run as a 4- or 3-cylinder engine to save fuel, per fueleconomy.gov.
How much gas does cylinder deactivation save?
Fueleconomy.gov lists a potential efficiency improvement of up to 5%.
What is active fuel management?
Another name for cylinder deactivation. Fueleconomy.gov says it is also called multiple displacement, displacement on demand and variable cylinder management.
Is turbocharging better for fuel economy?
Fueleconomy.gov lists turbocharging with engine downsizing at up to 8% potential efficiency improvement, compared with up to 5% for cylinder deactivation. Real-world results vary by vehicle.
What is direct injection?
Gasoline direct injection sprays fuel directly into the cylinder instead of the intake port. Fueleconomy.gov says this can increase performance and lower fuel use, with a potential efficiency improvement of 1%.
What are your service hours?
Monday to Friday 8 a.m. to 5 p.m. and Saturday 8 a.m. to 4 p.m. We are closed Sunday.
Shopping for a used car?
Visit us at 1200 E. Chicago St. in Elgin.
Sources
Engine technology information and efficiency estimates are from fueleconomy.gov, the U.S. government fuel economy site administered for the Department of Energy and the EPA, read November 9, 2026. This is general information; your owner's manual is the authority for your vehicle. Our address and service hours are from our own website, checked the same day. Photo is of our dealership.
- Advanced Engine Technologies (fueleconomy.gov), U.S. Department of Energy and U.S. EPA, read November 9, 2026
- Service page: address and hours, Elgin Auto Sales & Service Center, read November 9, 2026