First Drive: 2012 Buick LaCrosse eAssist

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Like everything else in the LaCrosse, the direct-injection four-cylinder is impressively smooth, quiet, and refined. The transmission is programmed to rev the snot out of it in normal driving, giving the impression that this Buick isn’t arguing with your right foot -- and the end result is that a four-cylinder winds up being quite sufficient in a 3800-lb car.

Perhaps the most impressive thing about the LaCrosse is the refinement of its stop-start system. Without the tachometer needle dropping, you would never know that the car has switched itself off. There is no shudder, there is no nudge -- it is completely imperceptible. Likewise, there’s almost no sign that the engine is starting back up when you pull your foot off the brake pedal -- other than that the tach jumps up and the Buick starts to quietly creep forward.

Getting credit for this (in addition to the engineers’ masterful programming) is the belt-driven motor/generator under the hood. This device replaces the alternator, and is used for stop/start, to assist the engine under acceleration, and for brake-energy regeneration. It can contribute 15 hp and 79 lb-ft of torque to the engine’s output and generate a maximum of 15kW (20 hp) of electricity under deceleration. Using a belt, instead of gears, isolates the motor/generator from the driveline, so it’s completely silent in operation.

The Buick LaCrosse eAssist doesn’t use a typical hybrid blended brake master cylinder, so its brakes feel no different than any other nonhybrid vehicle. This is a very good thing. Like last year’s four-cylinder model, it uses electric power steering, which isn’t nearly as natural feeling as the hydraulic steering in the V-6 model, but does completely eliminate torque steer.

The best part about the LaCrosse, though, is that from behind the wheel, there’s no real price to pay for the enormous (31.5% city, 20% highway) fuel economy benefits. The eAssist drives just as well as the regular LaCrosse did. Smooth, quiet, and comfortable -- and that’s exactly what Buick customers want. Just with far better fuel economy.

The LaCrosse now starts at $30,820, a jump of nearly $3000 compared to last year’s base four-cylinder model, but Buick has made significant additions to the standard equipment list, including dual-zone climate control and alloy wheels.

We’re big fans of the one-price, choose either V-6 power or compact-car fuel economy strategy. Especially in this case, where the V-6 receives 23 hp more and the four-cylinder is not only faster, but significantly more fuel efficient. We’ll be watching the model mix carefully -- whether buyers opt for the four or six-cylinder will speak very clearly about entry-level full-size luxury buyers’ priorities.