Buick is continuing the eAssist powertrain for its 2013 Regal, which finds its way to dealers this fall.

"With eAssist, Buick is redefining what a 'conventional powertrain' means to customers," eAssist global chief engineer Stephen Poulos said in a statement. "It changes the fuel economy - but not the experience - for the 97 percent of new car buyers who aren't buying hybrids."

Buick describes eAssist, which gives the Regal and LaCrosse capability of 36 mpg, as a much simpler system than the large, heavy batteries and electric motors of a hybrid vehicle. eAssist uses a compact lithium-ion battery and a small electric motor/generator instead of an alternator.

Buick describes three functions that help eAssist achieve fuel efficiency:  a stop/start feature that turns the engine off when the car is at rest; regenerative braking that stores energy that would otherwise be lost during braking; and an electric motor that assists the engine on inclines or during acceleration.

"It takes advantage of the best parts of a hybrid, and eAssist is now standard equipment for Regal," said Poulos. "These new functions happen seamlessly, a requirement for Buick drivers who demand a refined driving experience. They'll really only notice a difference at the pump."

Consumers who want even more acceleration can choose, at no additional cost, a 220-horsepower, 2.0-liter turbocharged Ecotec engine; or they can opt for the 270-horsepower Regal GS, both of which feature variable valve timing and direct injection.

Buick calls the GS's engine one of the most power-dense ever certified by the Society of Automotive Engineers. It offers high-performance Brembo brakes and HiPer strut suspension technology, as well as enhanced design cues inside and out.

The Regal Turbo and Regal GS are both offered with automatic or manual transmissions; while Regal with eAssist is available solely with a six-speed automatic transmission.

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