The C-Max Energi has an EV mode button on the center stack that lets the driver choose between three modes: electric-only driving, normal hybrid mode (which blends electric and gasoline engine power as appropriate) or EV-later mode, which reserves the battery pack power for later use.
Thanks to BMW's four-mode driving-dynamics software which ratchets up the responses of the steering, suspension, engine, transmission and brakes the 640i has a broad performance envelope, from sluggardly to aggressive.