DETROIT – Ford Motor Co’s upcoming C-Max Energi plug-in hybrid-electric vehicle may have a speed-limited electric-only mode, much like the auto maker’s hybrids, a top engineer says.

Introduced at the North American International Auto Show here, the Ford C-Max Energi is powered by an Atkinson-cycle 2.0L 4-cyl. internal-combustion engine, paired with a permanent magnet electric motor powered by a lithium-ion battery.

But unlike the Chevy Volt extended-range EV, which can travel up to 50 miles (80 km) at highway speeds before the gas engine kicks in to power an electric generator that drives the wheels, the Energi will employ an updated version of the powertrain used by Ford’s other hybrids, only with a larger lithium-ion battery.

The Fusion Hybrid is able to travel up to about 47 mph (76 km/h) before the gasoline engine takes over, and the new C-Max Hybrid is expected to boost that figure, but likely not up to highway speeds.

Nancy Lee Gioia, Ford's director -global electrification, hints that may be the same case with the Energi. “Sometimes when you try to drive excessive speeds or at high acceleration rates, it’s a system tradeoff,” she tells Ward’s.

“In order to accelerate at a high rate (in electric mode), you tend to need to oversize the battery. That (large battery) is something you don’t use all the time, and you’re carrying around all that extra weight,” she says.

But Gioia says at Ford it’s not about one-upping the competition but rather offering a real-world solution that accommodates most customer needs at an affordable price. “From our perspective, it’s important is to have the right type of functionality for the customer’s needs.”

Gioia reveals Ford considered offering a vehicle similar to the Volt, also known as a series hybrid for its extended-range, but various studies concluded it would be too expensive due to the need for a larger Li-ion battery.

“If you’re driving down the road and come to a long hill, in a series configuration to make it up that hill and maintain your speed and not run into degraded performance, you have to make the battery larger and possibly the engine larger to maintain (your speed).”

Gioia declines to disclose the size of the Energi’s battery but hints it’s considerably smaller than the Volt’s Li-ion battery.

bpope@wardsauto.com