LaCrosse with eAssist Delivers Fuel Economy of a Small Car

Buick uses electrification and other improvements to get estimated 37 mpg highway

OSHAWA As gas prices go up, so does purchase consideration for more fuel-efficient cars. And the new 2012 Buick LaCrosse with eAssist, a luxury sedan that comfortably seats five adults, delivers highway fuel consumption on par with compacts like the Mini Cooper.

LaCrosse with eAssist, which goes on sale this summer, uses a variety of technological advances and body enhancements to deliver estimated segment-leading fuel consumption rating of 5.4L/100km on the highway and 8.0L/100km in city driving without sacrificing passenger comfort.

Not only is the luxury sedan expected to be more fuel efficient than competitors like the Acura TL, Lexus ES350 and Lincoln MKS, it also expects to beat smaller hybrids, including the Toyota Camry Hybrid and Lexus HS Hybrid on the highway, while offering more rear leg room than any of them.

LaCrosse is the first in its segment with a four-cylinder, six-speed powertrain, the first with HiPer Strut suspension for improved ride and handling, and now available eAssist technology.

Program engineers improved the fuel efficiency of the outgoing four-cylinder, six-speed 2011 model by 24 per cent by implementing a number of improvements. Chief among them was the introduction of the electric assist (eAssist) system that is mated to a 2.4L Ecotec direct injection four-cylinder engine and a next-generation six-speed automatic transmission.

The eAssist system uses a state-of-the-art 115V lithium-ion battery system and latest-generation 15-kW electric motor-generator to enable regenerative braking, which takes place anytime the driver is off the throttle. Regenerative braking provides up to 15 kW of electricity to charge the battery to power all of the vehicles electrical systems with recaptured energy instead of fuel, which dramatically reduces the need to load the engine with the generator.

The system uses power stored in the battery to provide 15 hp of electric power assistance in various driving scenarios, delivering more than three times the power provided by the previous-generation belt-alternator-starter system.

The additional 15 hp provided by electric assist allowed us to lower LaCrosses gear ratio without sacrificing reserve acceleration and performance, said Steve Poulos, global chief engineer of the eAssist system. For example, when climbing the grade of an overpass, a normal vehicle will downshift and lose some fuel efficiency, but LaCrosse with eAssist maintains gear for improved performance and increased efficiency.

eAssist also enables LaCrosses Ecotec engine to shut down fuel delivery in certain deceleration conditions, which saves additional fuel. 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. Then, as the vehicle comes to a stop, the motor-generator unit spins the engine, bringing it to a smooth stop properly positioned for a smooth restart.

All Buick automatics do some deceleration fuel cutoff when the driver is not on the accelerator, said Daryl Wilson, LaCrosse lead development engineer. But eAssist allowed us to take the decel fuel cutoff all the way down to zero speed, which resulted in a significant fuel consumption improvement.

Program engineers also improved LaCrosses underbody aerodynamics by strategically placing underbody aero panels. Tires were optimized for performance and fuel efficiency, and electronically controlled shutters in the lower grille close at higher speeds to push more air over the vehicle, which increases aerodynamic efficiency to improve fuel consumption and engine warm-up.All of these technologies increase the effectiveness of the eAssist systems regenerative braking capability, while also improving the vehicles efficiency while driving.

LaCrosse with eAssist includes an ECO gauge on the instrument panel that continuously responds to driving behaviour, helping the driver attain maximum efficiency. It also features a hill-assist system that captures brake pressure to help the driver more comfortably accelerate from a stop on a moderate or steep grade. It does this by greatly reducing the tendency of the vehicle to roll backward with the engine in shut-down mode.

The eAssist system also comes to Buick Regal in late 2011.

About Buick in Canada

Buick is a modern luxury brand offering vehicles with sculpted designs, luxurious interiors with thoughtful personal technologies, along with responsive-yet-efficient performance. Buick is attracting new customers with its portfolio of award-winning models, including the Enclave crossover, LaCrosse sedan, Regal sport sedan and highly anticipated all-new 2012 Buick Verano compact luxury sedan. Buick is the fastest growing major brand in North America and remains a best-selling brand in China, with continuing record growth. Learn more about Buick cars and crossovers at


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