NHTSA Complaint #11566790 — 2021 TESLA MODEL Y

1. Under certain circumstances, the vehicle is able to decelerate using its regenerative braking system without illuminating the brake lights. This occurs during "one pedal driving" where the operator is driving only using the throttle to both accelerate and decelerate the car, without the input of mechanical brakes. This is a programming issue, not a mechanical issue. The brake lights are "triggered" when the car decelerates at a threshold of -0.1G or greater. At anything less than -0.1G, the lights will not turn on. This drastically increases the risk of a rear-end collision. 2. Under the right conditions the operator could decelerate from a speed of 45 mph to 5 mph without the brake lights ever coming on, not until they reach a near-complete-stop. This poses a high risk to all drivers that are behind the vehicle, and fails to give warning to other drivers. It should never be possible for this to occur. 3. This problem has been in discussion on Tesla owner's forums; specifically "Tesla Motors Club". (see attached posts) Tesla has the highest accident rate, and no one has yet figured out why. A typical internal combustion vehicle equipped with an automatic transmission coast-down decelerates at an average rate of -0.02G. The Tesla's regen brake light turn-on threshold of -0.1G is 5X more than the deceleration of a typical coasting ICE car (-0.02G) . For slow-downs between -0.02G and -0.1G, where the Tesla's deceleration exceeds an ICE car by up to 5X, there is no warning to other drivers, as the brake lights will not turn on. Any braking force above -0.02G of deceleration exceeds that of an ICE car, and should be made-known via the brake-lights. I hope that this is not overlooked; it is extremely important for this to be addressed to reduce rear-end collisions involving EV's. 99%+ of vehicles in the USA are ICE, and do not coast-down at a rate of -0.1G. The brake lights must indicate this above-normal reduction in speed.