Buick has announced that it will begin selling an extra fuel-efficient version of the Regal in the fall. Called the 2012 Buick Regal eAssist, this compact sedan is what we would call a "mild hybrid," a car that's expected to get an impressive 26 mpg city/37 mpg highway, thanks to fuel-saving technology that is said to improve overall economy by 25 percent over the 2011 4-cylinder/6-speed automatic powertrain.
This Regal joins the 2012 LaCrosse as the second Buick to feature the eAssist technology, which uses a state-of-the-art lithium-ion battery system together with an electric induction motor-generator and regenerative braking to improve fuel economy.
"Buick's eAssist technology means customers don't have to trade a premium driving experience for efficiency," said Tony DiSalle, vice president of Buick marketing. "We believe Regal and LaCrosse with eAssist provide more logical and affordable choices, compared to other hybrid midsize and full-size luxury sedans."
It's All in the Assist
The eAssist system mates to the Regal's 2.4-liter direct-injected 4-cylinder engine and 6-speed automatic transmission. It uses power stored in the battery for electrical boost in various driving scenarios, optimizing engine and transmission operation. A 115-volt lithium-ion battery and 15-kW induction motor-generator help increase fuel economy by providing up to 11 kW (15 hp) of electric power assistance during acceleration. The system also features automatic engine shut-off when the vehicle is stopped, aggressive fuel cut-off during deceleration down to zero vehicle speed, which is enabled by the torque smoothing provided by the induction motor-generator unit. Moreover, the Regal eAssist will have an intelligent charge/discharge of the high-voltage battery and regenerative braking to charge the battery.
"The capability to deliver electric boost to the powertrain system during heavy acceleration and grade driving enables the engine and transmission to operate more efficiently," said Steve Poulos, global chief engineer of the eAssist system. "Full fuel shutoff at stops and during deceleration complements electric boost and regenerative braking with additional fuel savings."
The 2012 Regal eAssist has improved underbody aerodynamics and tires optimized for performance and fuel economy. Also, on grades, a hill-assist system will capture brake pressure to help the driver more smoothly and comfortably accelerate away from a stop by reducing the tendency of the vehicle to roll backward when the engine is in shut-down mode.
"The battery system is designed to provide power assistance to the internal combustion engine, rather than store energy for all-electric propulsion," said Poulos. "It's really an extension of the conventional internal combustion engine, not a replacement for it."
The eAssist power pack, located in a compartment between the rear seat and trunk, contains the lithium-ion battery pack, the integrated power inverter and 12-volt power supply. Although Buick says the system is compact and lightweight, weighing only about 65 lb., the trunk space is reduced a bit. An electric fan cools the power pack, drawing air from a vent located in the package tray, behind the rear seat.
As with the LaCrosse with eAssist and other GM mild hybrids, the electric induction motor-generator replaces the alternator and provides both motor assist and electric-generating functions through a unique engine belt-drive system. The induction motor-generator is a high-performance, compact induction motor that is liquid-cooled for increased performance and efficiency.