Also known as: Robotised manual; clutchless manual; semi-automatic gearbox; ASG; EGC; ETG
The VW Up is a great little car, but its jerky ASG gearbox is best avoided
Continuously Variable Transmission (CVT)
A continuously variable transmission doesn’t have cogs in it, like most gearboxes. Instead, it uses two pairs of metal cones, each arranged pointy end to pointy end. One set of cones is attached to the engine, and the other is attached to the wheels. A belt is then suspended between these pairs of cones. As the cones move toward and away from each other, usually controlled by a computer in modern systems, the angle of the belt between the pairs of cones changes, thus altering the gearing.
It sounds bizarre, but it’s very efficient, because instead of needing fixed ratios, the gearing can be adjusted almost infinitely. This means the engine can be kept at its most efficient speed while the car accelerates, and it also means that there are no gearchanges, which makes progress seamless.
The one major downside is that a CVT gearbox can make the car irritatingly noisy under acceleration, because the sound of the engine stays at a constant pitch, rather than rising and falling as it would with a more conventional gearbox.
Also known as: Belt-and-pulley; E-CVT; Multitronic