A regenerative braking system for a vehicle includes a displacement on
demand (DOD) engine having cylinders, a battery, and an electric machine
having motor and generator modes. The electric machine is selectively
driven by a wheel of the vehicle. A controller detects a braking
condition of the vehicle and deactivates at least one of the cylinders in
response to the braking condition. The controller operates the electric
machine in the generator mode during the braking condition to charge the
battery.