By Jim MacPherson
A quick glance at the Buick LaCrosse will reveal none of the significant changes that have taken place for 2012. The styling remains the same; it’s what’s under the hood that’s new.
The more traditional drivetrain uses last year’s V-6 engine. However, the 3.6-liter motor has been retuned, raising its output from 280 to 303 horsepower.
Of greater significance, last year’s 2.4-liter four-cylinder engine has been paired with an electric motor-generator and lithium-ion battery pack that turns this model into a mild gasoline-electric hybrid. Buick calls the drivetrain eAssist, and claims it is good for a 25 percent improvement in fuel economy, compared to last year’s LaCrosse with the 2.4-liter four cylinder.
The response so far depends on the customer, according to John Bekish, Internet manager at Parsons Buick of Plainville. “Seventy-five percent go for the V-6. Some people are afraid of a four-cylinder, thinking that they can’t go up a hill without a climbing lane. But people who drive it say, ‘I could live with this and it gets better gas mileage, why not?’”
General Motors has chosen an interesting approach in making the LaCrosse a hybrid. Rather than sandwiching a thin motor-generator between the engine and transmission, GM hangs it just off the engine where the alternator is usually found. Here, it is driven by the serpentine belt (also called a fan belt, though engine cooling fans today are not usually belt driven). However, it also transmits power to the engine through this belt.
This means that when the gasoline engine could use a little more power, the electric motor-generator delivers it. This added power can be used for acceleration or, on the highway it can take the place of a downshift from the new six-speed automatic transmission. Indeed, the last four-cylinder LaCrosse we tried was constantly downshifting on the highway. Even the hint of a mild upward incline prompted a one-gear reduction and the steep hills on I-84 near the Massachusetts border resulted in dramatic downshifts, some of them noticeable.
With the eAssist drivetrain, the electric motor-generator significantly reduces this downshifting propensity. In greater Hartford, only Sunset Ridge on I-84 prompted a single downshift. Milder uphill grades required no action from the transmission, a fact made all the more impressive by the lower final drive ratio used this year. This will boost fuel economy but should, in theory, give the transmission more work to do.
“People are surprised to learn that whenever they take their foot off the gas, they’re using no fuel,” Bekish says. Other fuel-saving enhancements include louvers in the grille and underbody panels to reduce air resistance.
As a mild hybrid, the LaCrosse never runs on electric power alone. It does, however, shut the engine off at stops. When the driver releases the brake pedal, the gasoline engine uses the motor-generator to restart. A standard starting motor cranks a cold engine.
Performance is satisfactory. Our zero-to-60 time came to 9.1 seconds, though the LaCrosse felt faster than this number suggests. The 2.4-liter four-cylinder engine turns in a suitably refined performance. We managed just over 28 miles per gallon.
The eAssist package asks little of the driver, with the only penalty coming in the trunk. Here, the lithium-ion battery pack gobbles up some space and limits the trunk pass-through with a folded rear seat to the driver’s side.
The LaCrosse now has seven different trim lines, up from three last year. They are: Base, Convenience, Leather, Premium, Premium II, Premium III and Touring. The first four trim levels use the eAssist drivetrain. The V-6 is a no-cost option in the Convenience, Leather and Premium trims. Premium II, Premium III and Touring versions come only with the V-6 engine. Buyers can also forsake front-wheel drive for optional all-wheel drive on V-6 powered Leather, Premium and Premium II models.
This LaCrosse remains both pleasant and competent. With the added fuel economy, its appeal should go well beyond Buick’s traditional customers.
Engines: 2.4 eAssist 3.6
HP 197 (182 from gas/15 electric) 303
Torque 172 264
EPA 25/36 17/27 (16/26 with AWD)
Next Week: Toyota Camry