To get an accurate reading of how a plug-in hybrid electric vehicle performs in battery-only mode and in overall extended range, two experiences are useful: lots of behind-the-wheel driving time under various driving conditions (altitude, climate temperature, average speed driven, stop-start, etc.) or a detailed conversation with the chief engineer who designed the car.
Brad Berman, editor of PluginCars.com and HybridCars.com, got a bit of both. He had a conversation with John Davis, Ford's chief engineer for the C-Max in North America, that clarified how the upcoming C-Max Energi differs from the Toyota Prius Plug-in Hybrid in battery only and extended range modes. Berman issued a mea culpa after having criticized Ford for seemingly hyping up the superior capabilities of the C-Max Energi. "I learned that the C-Max Energi is indeed substantially more capable of driving purely as an EV than the Prius Plug-in," Berman writes.
Berman drove the Prius Plug-in Hybrid during a three-day loan and found it could go about 11 miles on all-electric driving, which matches the official EPA estimate, versus Ford's claim that the real number is six miles of battery only range. The distinction that Berman was able to clarify in talking to Davis is how to determine the vehicle's true "keep this thing in all-electric mode." Ford's "EV Now" button in the C-Max Energi allows the driver to access the battery-only driving experience better compared to the Prius Plug-in Hybrid's "relatively wimpy all-electric experience."
The "EV Now" feature makes the C-Max Energi much more like a Chevy Volt, Berman says. C-Max Energi drivers also have the option of using its "EV Later" button, which is similar to the Volt's Mountain Mode, to save battery power for later use, or they can keep the plug-in in "EV Auto" mode, in which the car operates more like the conventional C-Max hybrid.