Buick makes the eAssist system standard on the 2012 LaCrosse sedan.
There are plenty of small cars on the market now nudging into 40 mpg territory, but for those who want great mileage, the sacrifice is usually in the form of roominess and comfort. Buick, with the debut of the new eAssist system – standard on the 2012 LaCrosse – aims to let buyers have their automotive cake and eat it, too.
The 2012 Buick LaCrosse with the now-standard eAssist system also demonstrates that smaller, hybridized powertrains can actually deliver a peppy, even more aggressive ride than the V-6s and V-8s Americans are used to.
Using a variety of technology and exterior enhancements, the 2.4-liter, Ecotec 4-cylinder engine on the 2012 Buick LaCrosse with e-Assist gets an estimated 36 miles per galon on the highway and 25 mpg in the city. That represents a 20% improvement in highway mileage and a 32% boost in city mileage over the V-6 package of prior years.
How does it get there?
A closer look at the eAssist system from underneath the 2012 Buick LaCrosse.
“The eAssist system integrates regenerative braking with the latest lithium-ion battery technology, for significant fuel-efficiency gains,” said Steve Poulos, global chief engineer of the system.
The MRSP is $29,960 before an $860 destination charge, which is $2,000 more than the 2011 LaCrosse equipped with a 4-cylinder. The 4-cylinder LaCrosse without the eAssist is no longer available but GM will sell a 2012 LaCrosse with an optional V6 for those insisting on a more conventional powertrain.
“Providing electric boost to the powertrain system during heavy acceleration and grade driving helps the transmission operate more efficiently. The engine start-stop and fuel shut-off during deceleration features add to the fuel savings,” he said.
LaCrosse’s fuel economy rivals – or exceeds – that of small cars like the MINI Cooper with automatic transmission, at 28 city/36 highway, and the Toyota Corolla, at 26 city/34 highway with a 1.8-liter I-4 and automatic transmission. But it still provides a full-size luxury package with ample room for five adults.
“Given the uncertainty of today’s fuel prices, the LaCrosse with eAssist is a smart and timely choice for customers who seek excellent fuel economy and want the roominess and features of a full-size luxury sedan,” contends Tony DiSalle, U.S. vice president, Buick marketing.
The eAssist system works with the LaCrosse’s direct injected 2.4L Ecotec four-cylinder and next-generation six-speed automatic powertrain combination. With eAssist, the LaCrosse engine is rated at 182 horsepower, according to GM.
It uses power stored in an advanced, air-cooled lithium-ion battery to provide needed electrical boost in various driving scenarios, optimizing engine and transmission operation. An advanced 115V lithium-ion battery and latest-generation 15-kW motor-generator unit help increase fuel economy with regenerative braking, which provides electricity to charge the battery.
Essentially a “mild hybrid” — which means the 2012 LaCrosse cannot operate on battery power alone – the eAssist, as its name implies, is there to kick in power during take-off or hard acceleration. But it also comes into play during routine driving maneuvers, smoothing things out, for example, when you’re riding on rolling terrain. That translates into a less busy gearbox, for one thing.
The added electric power provided by the eAssist system allows for higher gearing to improve steady state efficiency without impacting acceleration performance or drivability. The system’s capability of providing some electric assistance at cruising speeds allows the driver to accelerate lightly or ascend mild grades without the transmission downshifting.
“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. “We believe this combination points to the future of vehicles powered primarily by an internal combustion engine.”
(Take a first drive in the 2012 Buick LaCrosse with eAssist. Click Here for the review.)
In addition to the efficiency of the eAssist system, the LaCrosse was also designed to be aerodynamically efficient to save even more fuel at highway speeds. It is one of the first vehicles to employ an active shutter system in the lower grille. That reduces wind turbulence when the engine needs less cooling, adding a small but measurable bit of fuel efficiency.
The system also shuts down fuel delivery in certain deceleration conditions, further improving mileage.
While in fuel shut-off mode, the motor-generator unit continues spinning along with the engine to provide immediate and smooth take-off power when the driver presses on the accelerator. As the vehicle comes to a stop, the engine’s start-stop function is active when the motor-generator unit brings the engine to a smooth stop to position it properly for a smooth restart when the brake is released.
The LaCrosse with eAssist not only rivals the fuel economy of small cars, it trumps the efficiency of non-hybrid segment competitors such as the Acura TL and Lexus ES 350, and is on par with the more expensive hybrid models such as the Lincoln MKZ and Toyota Camry hybrids, GM officials noted.
Assuming market acceptance of the new eAssist system, GM insiders confidently hint that the technology will expand to other Buick models — and migrate to products sold by other General Motors divisions, such as Chevrolet — over the next few years. It will complement the maker’s other, more advanced battery-based systems, such as the two-mode hybrid found in the Cadillac Escalade, and the plug-in drivetrain of the high-profile Chevrolet Volt.