GM is moving forward with its "tweener luxury" Buick brand and is looking to further expand its appeal with more fuel-efficient models. Late last year, Buick announced that it would bring its LaCrosse eAssist to market this year that will achieve 25/37 mpg (city/highway).

Today, Ward's Auto reports that the hybrid system will also be filtering down to the slightly smaller Buick Regal. The Regal eAssist will be powered by the same 180hp four-cylinder engine, 15hp electric motor (fed by a trunk-mounted lithium-ion battery pack), and 6-speed automatic transmission.

Ward’s reports that the Regal eAssist will also achieve the same fuel economy as the LaCrosse eAssist. However, the powertrain will not come as standard equipment as it will on its more expensive big brother. 

“It’s a very integrated powertrain system, with no compromises in driving performance, shift quality or ride and handling,” said Daryl Wilson, LaCrosse lead development engineer of the eAssist system in November 2010. “We believe this combination points to the future of vehicles powered primarily by an internal combustion engine.”

The standard 2011 Buick Regal starts at $26,245 and gets an unremarkable 19 mpg in the city and 30 mpg on the highway from its 182hp 2.4-liter four-cylinder engine. The eAssist model will no doubt cost at least a few thousand dollars more pushing it closer to the $30,000 price point.

For comparison, other midsize hybrids on the market like the Ford Fusion Hybrid ($28,990) and Hyundai Sonata Hybrid ($26,545) offer greater fuel economy ratings of 41/36 and 35/40 respectively.

Updated 2/8/2011

General Motors has officially unveiled the Buick Regal eAssist, and the vehicle is officially rated at 26/37 (city/highway). It will go on sale later in the fall.