Propulsion calibrator Heisel explained that they took a different approach with the Bolt than previous hybrids and EVs. Most such vehicles phase out the regenerative braking at about 5 mph and blend in friction braking to bring the vehicle to a stop and hold it. Having worked on such systems for hybrid vehicles before leaving the engineering ranks, I can affirm that this is actually quite difficult to do smoothly and consistently.
The instrument cluster display shows a confidence region of likely range based on your driving history
The Bolt uses only regenerative braking when backing off the accelerator pedal all the way to a stop. In drive, the deceleration is comparable to the engine braking you will see in a conventional car with an automatic transmission. Tap the shifter to engage low and the regen becomes much more aggressive, getting to about .25 g, comparable to the maximum braking that most drivers do in daily commuting. The regen-on-demand paddle increases that to about .3 g.
When the car is close to stopping, the system actually reverses the current flow, applying reverse motor torque to bring the car to a stop and hold it. For extended stopped periods when the car is on a grade, the stability control will actually apply the friction brakes to avoid draining energy needlessly and overheating the motor. Because the car is already stopped when the brakes are applied, it’s imperceptible.
