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Advanced Transmission Technologies

Adding gears allows your engine to operate at a more efficient speed more often, and the more gearing options your vehicle has, the more efficient it can be.

The table shows the efficiency improvements of more gears compared to a 4-speed automatic transmission.

No. of Gears Efficiency Improvement
5 2%–3%
6 3%–5%
7 5%–7%
8 6%–8%
Potential Efficiency Improvement: 2%–8%1
Savings Over Vehicle Lifetime:
Photo of continuously variable transmission

Most conventional transmission systems control the ratio between engine speed and wheel speed using a fixed number of metal gears.

Rather than using gears, CVTs use a pair of variable-diameter pulleys connected by a belt or chain that can produce an infinite number of engine/wheel speed ratios. Advantages include

  • Seamless acceleration without the jerk or jolt from changing gears
  • No frequent downshifting or "gear hunting" on hills
  • Better fuel efficiency

For more information, see How CVTs Work.

Potential Efficiency Improvement: 1%–7%1
Savings Over Vehicle Lifetime:

Also called dual-clutch transmission or direct-shift gearbox

Automated manual transmissions (AMTs) combine the best features of manual and automatic transmissions. Manual transmissions are lighter and suffer fewer energy losses but lack the convenience of an automatic.

AMTs operate similarly to a manual transmission except that they do not require clutch actuation or shifting by the driver. Automatic shifting is controlled electronically (shift-by-wire) and performed by a hydraulic system or electric motor. Some can even shift smoother than conventional manual transmissions.

Potential Efficiency Improvement: 7%–10%2
Savings Over Vehicle Lifetime:

* Fuel cost savings are estimated assuming an average vehicle lifetime of 166,000 miles,3 a fuel price of , and an average fuel economy of 22 MPG.4 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. Duleep, G. 2011. Comparison of Vehicle Efficiency Technology Attributes and Synergy Estimates.Adobe Acrobat Icon NREL/SR-6A20-47806.
  3. 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.
  4. 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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