What should you do to inform other motorists that you are slowing down unexpectedly?

Flashing your brake light is an effective way to communicate to other motorists that you are slowing down unexpectedly. This action visually alerts drivers behind you, allowing them to adjust their speed and maintain a safe distance. Brake lights are universally recognized as a signal for deceleration, making it a clear and immediate way to convey your intention to those following you.

Using turn signals typically indicates a change in direction rather than a decrease in speed. Sounding your horn is not a standard method for signaling a reduction in speed; it could lead to confusion or misinterpretation about your intentions. Moving to the side of the road is also not a signal for slowing down and might not always be a safe or feasible option, especially if you're still in the flow of traffic. Thus, flashing your brake light is the most direct and effective method for informing other motorists of your gradual decrease in speed.