Audi Continuous Variable Transmission

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A continuously variable transmission (CVT) (also known as a single-speed transmission, stepless transmission, variable pulley transmission, or, in case of motorcycles, a twist-and-go) is an automatic transmission that can change seamlessly through an indefinite number of effective gear ratios between maximum and minimum values. This contrasts with other mechanical transmissions that offer a fixed number of gear ratios. The flexibility of a CVT allows the input shaft to maintain a constant angular velocity.

A belt-driven design offers approximately 88% efficiency,[1] which, while lower than that of a manual transmission, can be offset by lower production cost and by enabling the engine to run at its most efficient revolutions per minute (RPM) for a range of vehicle speeds. Thus a small car can strike a balance between fuel efficiency and cost of manufacture.

When power is more important than economy, the ratio of the CVT can be changed to allow the engine to turn at the RPM at which it produces greatest power. This is typically higher than the RPM that achieves peak efficiency. Finally, a CVT does not strictly require the presence of a clutch. Nevertheless, in some vehicles (e.g. motorcycles), a centrifugal clutch is added[2] to facilitate a "neutral" stance, which is useful when idling or manually reversing into a parking space.

CVTs should be distinguished from power-sharing transmissions (PSTs), as used in newer hybrid cars, such as the Toyota Prius, Highlander and Camry, the Nissan Altima, and newer-model Ford Escape Hybrid SUVs. CVT technology uses only one input from a prime mover and delivers variable output speeds and torque, whereas PST technology uses two prime mover inputs and varies the ratio of their contributions to output speed and power. These transmissions are fundamentally different.

Some vehicles that offer CVT are the Ford C-MAX hybrid, the Mitsubishi Lancer, the Proton Inspira, the Proton Iriz, the Proton Saga FLX, the Proton Prevé, the Dodge Caliber, the Toyota Corolla, the Toyota iQ, the Honda Insight, Fit, CR-Z hybrid, Capa, Civic GX (CNG), Civic Hybrid, City, HR-V and Accord, the Nissan Tiida/Versa (SL, SV, and Note S Plus or higher models), Cube, Juke, Sentra, Altima, Maxima, 2013 1.2 Note, Rogue, X-Trail, Murano, Sunny and Micra, the Jeep Patriot and Compass, the Suzuki SX4 S-Cross, and the Subaru Forester, Impreza, Legacy, and Outback.

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