2012 Buick LaCrosse Electrified Buick

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Smart-looking and smart over the road: Buick’s 2012 eAssist LaCrosse.

ALONG WITH warmer winters and cheaper real estate, here’s something else to get used to: smaller engines in our cars. Just five years ago, the notion of a 16-foot, two-ton deluxe sedan with four cylinders under the hood would have been preposterous.

Now, though, this isn’t cheaping out, it’s being smart. Big motors use more fuel. The easiest way to make big motors smaller is to lop off a couple of cylinders—replace your V-12s and V-10s with V-8s, your V-8s with sixes, and so on.

But no one wants to give up performance, so carmakers are replacing those cylinders with turbochargers or, in Buick’s case, with electricity.

It’s not just another Prius-style hybrid drivetrain. Buick calls its eAssist innovation “light electrification,” and the combination of simplicity and ingenuity is not only appealing, it’s also effective. The basic powerplant is a 2.4-liter (146 cubic inches) four-cylinder gasoline engine that sends 182 horsepower and 172 pounds of torque to the front wheels.

Onto this, Buick has grafted a belt-driven, liquid-cooled, electric motor-generator and a 115-volt lithium-ion battery.

The LaCrosse cruises with the fuel-sipping efficiency of its small four; for merging into traffic, passing and climbing hills, eAssist adds 15 horsepower and 79 foot-pounds of torque.

The motor-generator replaces the alternator and it not only provides the extra power, it also recharges its own battery. Other features on eAssist Buicks include regenerative braking, seamless engine stop-start plus ample current for all the accessories when the vehicle is at rest, and fuel cut-off during deceleration.

The eAssist LaCrosse also has a shutter behind its grille that opens for engine cooling and closes for better aerodynamics, as needed. Even the car’s underbelly has been smoothed out with panels for improved air flow, which contributes to fuel economy.

Turbochargers reclaim energy that’s being shunted out the tailpipe; eAssist grabs energy from braking and deceleration that’s otherwise wasted.

Daryl Wilson, lead engineer for the LaCrosse, explains that the regenerative braking “is done via the automatic transmission, which transmits the braking energy to the motor-generator via the serpentine belt.

In most automatic transmissions, the torque converter locks up at highway speeds and releases as the unit downshifts.

Not in the LaCrosse. Our torque converter remains locked through all the downshifts, and the motor-generator smooths out what otherwise would be jolting shifts.”

The LaCrosse transmission is a new 6-speed automatic that can also be shifted manually. Driving was indeed smooth, with only a few abrupt low-speed gear changes in stop-start traffic.

Oddly, these diminished over time and then seemed to go away entirely. Our test car was brand-new; maybe it needed breaking-in?

In any event, Buick is so confident that it has given eAssist an eight-year, 80,000-mile warranty and promises that it will soon be available on the Buick Regal as well.

The new LaCrosse has earned an EPA economy rating of 25 miles per gallon in city driving, 36 on the highway and 29 combined. Buick says this is an improvement of about 25% over the previous gas-only LaCrosse.

My time in the car included a mix of highway and in-town driving at an average (according to the onboard computer) of 30.6 miles per hour and 26.9 MPG.

While no one would confuse it with a BMW 750Li or a Mercedes S550, the LaCrosse felt adequately powerful for a full-size premium sedan, and more luxurious than Cadillac’s steroidal CTS-V. With a sticker price of $38,175, it was also far, far less expensive.

Impressive as the engineering and value may be, Buick’s efforts will be futile if no one wants to drive the car. Well, I want to drive it, and I was sorry to see it go.

The LaCrosse is serenely quiet and comfortable at speed, composed and capable on bad pavement, and very spacious inside.

It is also an unusually handsome, even sophisticated design, especially for Detroit. If this is the lower-energy, lower-carbon, make-do future of the automobile, we can have no complaints.