The kick-down feature is designed to give maximum acceleration.
When the accelerator pedal is pressed right down past the point of resistance at full throttle, the gearbox will shift down to a lower gear, depending on road speed and engine speed, and the engine power will be fully exploited. The upshift to the next higher gear is delayed until the engine reaches maximum rpm.
WARNING!
Please note that if the road surface is slippery or wet, the kick-down feature could cause the driving wheels to spin, which could result in skidding.