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Advanced Engine Technologies

Also called multiple displacement, displacement on demand, active fuel management, and variable cylinder management

This technology deactivates some of the engine's cylinders when they are not needed. This temporarily turns an 8- or 6-cylinder engine into a 4- or 3-cylinder engine, saving fuel.

Potential Efficiency Improvement: 4%–10%1
Savings Over Vehicle Lifetime: *

Turbochargers and superchargers are compressors that force additional air into the engine's cylinders, allowing more fuel to be injected as well. The additional air and fuel create more power. This allows manufacturers to use smaller engines without sacrificing performance.

Additional Information: How Turbochargers Work

Potential Efficiency Improvement: 2%–6%1
Savings Over Vehicle Lifetime: *

Also called direct fuel injection, spark ignition direct injection (SIDI)

In conventional gasoline engines, fuel is injected into the intake port and mixed with air while the air-fuel mixture is drawn into the cylinder. In direct injection systems, fuel is injected directly into the cylinder, which makes the fuel-air mixture somewhat cooler. Cooler air allows higher compression ratios and more efficient combustion, increasing performance and lowering fuel consumption.

Potential Efficiency Improvement: 2%–3%1
Savings Over Vehicle Lifetime: *

Also called idle-stop or smart-start

These systems automatically turn the engine off when the vehicle comes to a stop and restart it instantaneously when the the brake is released or the accelerator is pressed, so that fuel isn't wasted for idling. Regenerative braking is often used to convert mechanical energy lost in braking into electricity, which is stored in a battery and used to power the automatic starter.

Potential Efficiency Improvement: 2%–4%1
Savings Over Vehicle Lifetime: *

Includes variable valve actuation, variable-cam timing, cam phasing, variable valve timing and lift electronic control (VTEC®, VANOS®, VVT-i®), etc.

Valves control the flow of fresh air into the cylinders and the flow of exhaust out of them. When and how long the valves open (timing) and how much the valves move (lift) both affect engine efficiency.

Traditional engine designs use fixed timing and lift settings, which are a compromise between the optimum for high and low engine speeds. Variable valve timing and lift technologies automatically alter timing and lift to the optimum settings for the engine speed and power.

Potential Efficiency Improvement: 1%–11%1
Savings Over Vehicle Lifetime: *

* Fuel cost savings are estimated assuming an average vehicle lifetime of 166,000 miles,2 a fuel price of , and an average fuel economy of 22 MPG.3 All estimates are rounded to the nearest hundred dollars.

View Data Sources...
  1. National Academy of Sciences. 2011. Assessment of Fuel Economy Technologies for Light-Duty Vehicles. The National Academies Press, Washington, D.C.
  2. Average MPG for 2011 vehicles based on Light-Duty Automotive Technology,Carbon Dioxide Emissions, and Fuel Economy Trends: 1975 Through 2013.Adobe Acrobat Icon. EPA, 2013. Table 2.1.
  3. Average of car and truck lifetime mileage estimates (rounded to the nearest thousand miles) based on Transportation Energy Data Book, Edition 33. Oak Ridge National Laboratory. Tables 3.12 & 3.13.
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