The hybrid system has two electric motors. When you encounter a large
hill, those motors are automatically taken advantage of. The gasoline engine
will rev to its most efficient high-power RPM. That provides thrust directly
to the tires, generates electricity for the motor, and recharges the
battery-pack all at the same time. So to the surprise of many new owners,
large hills don't drain the system. You'll still have plenty of reserve
power available when you reach the top.