GM Expands eAssist Mild Hybrid System to 2012 Buick Regal
At the 2011 Chicago Auto Show, Buick announced that the 2012 Regal will be its second vehicle to sport the eAssist mild hybrid system—following in the footsteps of the 2012 Buick LaCrosse. With an EPA estimated 26 mpg city and 37 mpg highway, the 2012 Regal with eAssist will be 25 percent more fuel efficient than the conventional four-cylinder Regal.
GM’s mild hybrid system utilizes a relatively simple 15 kW motor/generator mated to a 2.4 liter Ecotec four-cylinder engine with a 6-speed transmission and connected to a 115 Volt, 65 pound lithium-ion battery which is recharged via regenerative braking. The battery is built by Hitachi and tuned for quick power input and output instead of high energy storage, as with a full hybrid or electric vehicle.
“We’re going after the low hanging fruit of hybridization,” said Steve Poulos, Buick’s Global Chief Engineer for Mild Hybrid and Battery Electric Powertrains on a call with media. “We go after the things we can do with a simpler, lower cost electrical system and try and apply those to a mainstream conventional vehicle.”
Poulos added that GM is trying to lead in the “light electrification” arena. “We’ve done a lot of work on the Chevy Volt to try and lead at the high end of things and see how far can we take a technology, but we’re also trying to lead in this more foundational approach,” he said.
The eAssist system uses the energy stored in its batteries via regenerative braking to accomplish three things, as explained by Poulos on the call:
- “After we recapture energy from regenerative braking, the first trick we do is shut the engine off and turn it back on automatically every time you come to a stop. This is typically thought of as start-stop and it is one of the features that most hybrids have and we’re able to do that very smoothly with the motor/generator.”
- “The second thing we do is we shut the fuel off completely every time we decelerate and the extra torque of the motor/generator means that when you decide to change your mind in the middle of that, you can very smoothly drive away. You will have the very quick response time you need without having to relight the engine. We can do that very aggressively—much more so than on a conventional powertrain.”
- “The third thing we do is we provide electric boost during grade type maneuvers. When we get into a [uphill] situation we can apply extra boost from the electric motor and that will keep the transmission from downshifting. With this system we are able to go two final drive ratios more economical than the base vehicle.”
GM says that the end result of the eAssist technology is a car that has the same performance, drivability and comfort as other Buicks, but with higher fuel economy. Although slightly less robust, the system bears similarities to Honda’s mild hybrid technology.
Although eAssist isn’t as flashy as the technology used in the Chevy Volt, the potential for vast fuel savings is not being overlooked by G.M. It’s an effective and affordable technology that can be spread across entire lines of vehicles, much the way that Toyota, for example, wants to extend its hybrid technology to all its popular models. After all, it’s going to take some time for fully electric and plug-in hybrid technology to reach economies of scale, and begin to come down in price.
The 2012 Buick Regal with eAssist goes on sale in late 2011.