The four-cylinder LaCrosse is sure to appeal to some buyers, but there's no way it will put much of a dent in the six-cylinder mix. While roughly 80 percent of the best-selling midsize cars are four-cylinders, the LaCrosse CX's just doesn't have the punch — or the price or mileage benefit — to command that much of the market, especially in the premium class, where larger engines are popular and lower mileage is better tolerated.

Though it has a roomy backseat, the LaCrosse is Buick's midsize car. The full-size Lucerne will continue to be sold until the middle of 2011, at which time the LaCrosse will be considered Buick's flagship sedan. With more room both in the trunk and in all seating dimensions, the Lucerne remains an attractive alternative if space is what matters most to you.