Buick is going greener. In a few months, the American automaker plans to introduce the 2012 LaCrosse eAssist. The new green machine is expected to deliver 25 mpg-city/37 mpg-highway. By comparison, the 2011 LaCrosse (with the same 4-cylinder engine) delivered only 19 mpg-city/30 mpg-hwy. Such a rise in mpg can yield an impressive 30 percent gain in fuel economy.

Buick's innovative e-Assist is similar in principal to the belt-alternator-starter (BAS) hybrid-system previously used by other automakers - only much more improved.

The main difference between the original iteration of the BAS system and the newest design featured in…