There are several different types of 'automatic' transmission.

'Full' automatics: These are what we have been talking about in this section; they have a gearbox and torque converter to transmit the power to the driving wheels.

Semi-automatics: These have a gear lever but no clutch, so you change gear as normal but the car does the clutch bit for you.

Pre-selector systems allow a gear to be selected in advance and then activated when needed by pressing a pedal.

'Tiptronic' (Porsche) or 'Sensonic' (Saab) systems allow electronic sequential gear changing through + and - buttons or lever, usually built into the steering wheel (like in racing cars!). These cars have a clutch, but it's operated by an electronic motor rather than directly by the driver.

Constantly Variable Transmission (CVT): This old system was pioneered by DAF amongst others came back to life in the early 90's; it's found in small 'automatics' Rather than 'stepped' gears, this type of drive is infinitely variable and is controlled by accelerator pressure and speed. CVT usually has fewer selector choices than full automatics, typically: Park;Reverse; Neutral; Drive; and Low.