Buttons tend to be used for 'on/off' functions, such as engaging the pit-lane speed limiter system, while rotary controls govern functions with multiple settings, such as the traction control programme, fuel mixture and even the car's front-to-rear brake bias - all functions the driver might wish to alter to take account of changing conditions during the race. Among the most recent additions are the ‘boost button,’ used to call on the temporary additional power available in cars equipped with a KERS system, and controls for the moveable front wing.
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