"Performance") modes cause gear shifts to occur at higher RPM, to improve acceleration. "Economy" (also called "Eco" or "Comfort") modes cause gear shifts to occur at lower RPM to reduce fuel consumption. Manual controls Since the 1990s, systems to manually request a specific gear or an upshift/downshift have become more common. These manumatic transmissions offer the driver greater control over the gear selection that the traditional modes to restrict the transmission to the lower gears. Use of the manumatic functions are typically achieved either via paddles located beside the steering column, or "+" and "-" controls on the gear selector. Some cars offer drivers both methods to request a manual gear selection. Continuously variable transmission (CVT) A continuously variable transmission (CVT) can change seamlessly through a continuous (infinite) range of gear ratios, compared with other automatic transmissions that provide a limited number of gear ratios in fixed steps. The flexibility of a CVT with suitable control may allow the engine to operate at a constant RPM while the vehicle moves at varying speeds. CVTs are used in automobiles, tractors, UTVs, motor scooters, snowmobiles, and earthmoving equipment. The most common type of CVT uses two pulleys connected by a belt or chain, however, several other designs have also been used at times. Dual-clutch transmission (DCT) A dual-clutch transmission (DCT, sometimes referred to as a twin-clutch transmission, or double-clutch transmission) uses two separate clutches for odd and even gear sets. The design is often similar to two separate manual transmissions with their respective clutches contained within one housing, and working as one unit. In most car and truck applications, the DCT functions as an automatic transmission, requiring no driver input to change gears. The first DCT to reach production was the Easidrive automatic transmission introduced on the 1961 Hillman Minx mid-size car. This was followed by various eastern European tractors through the 1970s (using manual operation via a single clutch pedal), then the Porsche 962 C racing car in 1985. The first DCT of the modern era was used in the 2003 Volkswagen Golf R32. Since the late 2000s, DCTs have become increasingly widespread, and have supplanted hydraulic automatic transmissions in various models of cars. Automated manual transmission (AMT) Automated manual transmission (AMT), sometimes referred to as a clutchless manual, is a type of multi-speed automobile transmission system that is closely based on the mechanical design of a conventional manual transmission, and