What are two reasons for using downshift in a car?
1. Engine braking. Downshifting can help to slow down the car by using the engine to brake the wheels. This can be useful when driving downhill or when coming to a stop.
2. Passing. Downshifting can give the car a quick burst of power for passing or accelerating in general. This can be useful when merging onto a freeway, or when overtaking another vehicle.