An EU standard applies where electric vehicles must illuminate their brake lights if the rate of deceleration exceeds 1.2 metres per second, but depending on the individual vehicle and what mode the regenerative braking is set to, it is possible to bring an EV to a halt without illuminating the brake lights. This may also occur if the driver is using one-pedal driving mode and does not fully release the accelerator, causing the vehicle to slow relatively rapidly without the brake lights being illuminated.

Many manufacturers are aware of this issue and are looking at possible solutions, such as lowering the threshold at which the brake lights are illuminated, but in the meantime it is a sensible approach to use brake lights as an indicator of intent and consider the distance between you and the vehicle in front as key measure of relative speed.