Buick makes the eAssist system standard on the 2012 LaCrosse sedan.
We’ve come to think of hybrids as an expensive option – requiring a buyer to pay an often stiff premium in exchange for higher mileage. But Buick has something different in mind.
Starting in August, the General Motors division will offer its LaCrosse sedan in two new ways, with an improved 3.6-lirer V-6 engine that adds 26 more horsepower, or with a 2.4-liter Ecotec four-cylinder engine with its new eAssist mild hybrid system, which will be standard equipment, not an option.
Buick says the combination of the gasoline engine and the power booster will improve fuel mileage to an EPA 25 city, 36 highway, best in class, without the cost, weight and complexity of a full hybrid system.
The eAssist system is a combination of a 32-cell lithium-ion battery pack, a motor/generator unit, the control electronics, and a clever belt-drive system that adds torque directly to the engine’s crankshaft. It’s an on-demand system designed to be used for startup acceleration, long uphill grades, and freeway on-ramps, adding about 15 horsepower to the engine’s 182 horsepower and 172 foot-pounds of torque.
A closer look at the eAssist system.
Driving eAssist one discovers that it delivers a solid, if not spectacular bump in acceleration when needed. Performance is closer to that of a V-6, thanks to the added power of the electric driveline.
But it also offers another more subtle advantage. During routine driving, the new hybrid driveline smooths things out. You may not even notice, at first, but it tends to eliminate the transmission hunting-and-shifting that is common with a small inline-four engine. That extra bit of power helps hold gears until you really need a downshift.
The eAssist uses a brushless, magnetless 15-horsepower induction motor with its own liquid cooling system, a motor that becomes a 20 horsepower generator, with peak torque of 110 foot-pounds. The regenerative braking system adds power to the battery whenever the car is coasted or braked.
Power from the engine and motor is transmitted to the front tires by a new 6-speed automatic transmission specially adapted for this application, using an electric oil pump to maintain pressure when the engine is stopped during a built-in start-stop function. The final-drive ratio has been raised considerably, from the 3.23:1 used currently with the 2.4-liter four up to 2.64:1 with the eAssist system for better highway fuel economy.
Shutters close behind the grille to improve aerodynamics.
Buick says that the compact, lightweight system adds only about 13 pounds of weight to the car, with the battery pack and control electronics in an air-cooled compartment in the trunk and the motor/generator mounted to the engine where a normal alternator would be, connected to the crankshaft by a push-pull pulley and belt system. The trunk still retains about 60 percent of the LaCrosse’s normal pass-through space on the left side for long objects like skis.
The eAssist package also includes automatic shutters in the grille that shut at road speeds over 30 mph to improve aerodynamic drag on the body, a chassis fitted with a front spoiler and flat panels underneath the car to minimize chassis drag, Michelin P235/50R-17 low-rolling-resistance EnergySaver tires on standard alloy wheels, and a system monitor in the instrument panel.
A closer look at the eAssist system from underneath the 2012 Buick LaCrosse.
The Buick LaCrosse eAssist will be built for North American consumption in Fairfax, Kansas, and will also be built and sold in China as a Buick LaCrosse and built and sold in Korea as a Daewoo Alpheon. The domestic version will sell for $30,820 base MSRP, with the new and improved V-6 engine and 6-speed transmission as a no-cost option to the Ecotec four with eAssist.
The improved 3.6-liter V-6 engine will carry a new rating of 303 horsepower and 264 foot-pounds of torque, now with cast-in integrated exhaust manifolds, a composite intake manifold, direct fuel injection and variable valve timing on both intake and exhaust camshafts. Buick says that’s an improvement of 23 horsepower.
The new V-6 engine will also be offered in an all-wheel-drive version of the LaCrosse later in the model year, and the eAssist system will be added to the powertrain lineup in the smaller Buick Regal as well.
Additional standard equipment on the 2012 Buick LaCrosse will include dual-zone climate control, 17-inch alloy wheels, Bluetooth, and USB connectivity. Later in the year, the LaCrosse with eAssist will be offered with GM’s new IntelliLink voice-activated and touch-screen interface and control system for smartphones and music players as standard equipment.