Here is a hint that often works in daytime traffic. If the motorist being tailgated flicks on and off, on and off, with the auto's regular headlight switch that tailgating driver may think the front auto is stopping and he may fall back. It has worked for me.
In today's autos the brake light and the rear red light often share the same housing and are indistinguishable from each other. Thus the front car appears to be slowing or stopping while still maintaining speed.