By Ben Klayman

SAN FRANCISCO (Reuters) - General Motors Co aims by 2017 to buld up to 500,000 vehicles a year that include some form of electric power in the engine, including cars like the Chevrolet Volt plug-in hybrid, a top executive said on Wednesday.

GM has made rolling out cars with electrical technology -- including its eAssist system that boosts fuel efficiency in gasoline-powered cars -- a central part of its global strategy, global product development chief Mary Barra told reporters.

"Our plans call for producing up to 500,000 vehicles annually with some form of electrification globally by 2017," she said via satellite.

That would be slightly more than 5 percent of GM's global sales last year of about 9 million.

The forecast includes plug-in hybrids; pure electric vehicles like the Chevy Spark EV that will go on sale next summer; and eAssist system, which GM offers on several vehicles, she said. GM introduced the Volt in the fall of 2010.

So far this year, GM has sold more than 50,000 vehicles that include electrification technologies in the United States, with eAssist accounting for slightly more than half that total. Barra did not break down how much of GM's target would be cars that do not include a gasoline engine, but she said plug-in technology will remain central to GM's strategy.

"A major focus for GM's electrification strategy will center on the plug," she said. "We have every intention of maintaining our leadership position in plug-in vehicles."

Barra said GM is not turning its back on traditional hybrid or hydrogen fuel-cell vehicles.

GM plans call for its eAssist system, which boosts fuel efficiency as much as 25 percent in some gasoline-powered vehicles, to be on "hundreds of thousands" of vehicles annually by 2017, she said.

Barra said the Spark EV minicar, which will take on Nissan Motor Co's Leaf, will be a global vehicle, launching first in select markets in the United States and South Korea before moving to other countries. GM will sell the car, rather than limiting access to lease deals, she added.

"We're not building the Spark EV to check a regulatory box," Barra said.

The EV's battery will be made by A123 Systems Inc, which filed for bankruptcy last month.

The rollout of the Spark continues GM's push to seize the mantle of "greenest automaker in the world" from Toyota Motor Corp, which makes the popular Prius hybrid car. Toyota also sells a plug-in version of the Prius as well. Continued...