Buick’s Regal GS sedan has won praise from consumers and automotive media alike. It’s an entertaining-but-comfortable sporty sedan that handles far better than anything in Buick’s recent lineup, and even the asking price is a bargain compared to competitive products from Japan or Europe.

The Achilles heel of the Regal GS, until now, at least, was that it only came with a six-speed manual transmission. That made it fun for weekend driving, but tedious for the Monday through Friday commute in rush hour traffic.

Buick knows this, so it’s just announced a six-speed automatic transmission as a no charge option for Regal GS buyers. Built by Aisin, the transmission is calibrated specifically for the Regal GS and matches the 0 - 60 mph acceleration time of 6.7 seconds achieved by the manual-equipped car.

Automatic-equipped Regal GS models will get Driver Shift Control, allowing owners to manually row through the gears. As on manual-transmission cars, selecting “GS” mode will tighten the suspension and improve throttle response, but will also quicken shifting on automatic transmission models.

Also new for the 2013 Buick Regal lineup is a change of engines in non-turbocharged models. The entry-level 2.4-liter four will be dropped from the lineup, replaced by the 2.4-liter eAssist mild-hybrid drivetrain. The eAssist engine was introduced on the larger Buick LaCrosse for the 2012 model year.

The eAssist system combines a conventional gasoline engine with a compact lithium-ion battery pack and small electric motor. At low speeds, the electric motor provides supplemental power, aiding acceleration and improving fuel economy. The system’s lithium-ion battery pack is recharged via regenerative braking.

Equipped with the eAssist drivetrain, the Buick Regal will achieve an EPA estimated 36 mpg highway, which is a significant improvement over the current model’s 31 mpg highway rating. The eAssist drivetrain will be used on Base and Premium Regal models, with Regal Turbo and Regal GS drivetrains remaining unchanged.