For decades, autos have used a two-state system to signal to drivers behind your car what your car is doing: The brake light is either ON = brakes on, or OFF = no brakes. With the current system, a completely-motionless car can still have the brake lights either ON or OFF, so it is NOT a reliable indicator. Add a few colored LED's and some signals from the engine and navigations computers, and VOILA a 4-state system 1. Acceleration (throttle applied) = Green 2. Coasting (no throttle and no brake) = Yellow or Amber 3. Brake application = Red Indiana University - Bloomington, Indiana tested such a system on a Ford Pinto in the early 1970's, long before inexpensive LED's and on-board computer technology.