Buick sales have dropped for 7 straight months, tied with Cadillac for the longest losing streak among the 41 brands sold in the United States. But unlike Cadillac, which has 2 new nameplates coming this summer, Buick doesn't have new or redesigned vehicles riding to the rescue.

The question confronting Buick is whether the slump is a sign of deeper troubles or simply growing pains now that GM finally has gotten serious about positioning Buick to challenge entry-luxury brands such as Acura and Infiniti

Despite GM's efforts to position Buick against import luxury brands such as Acura and Infiniti, research shows that consumers lump Buick with brands such as Ford and Toyota. In April, those were the 2 most-shopped brands by consumers who also were considering a Buick, according to Edmunds.com.

Until the new lease plan, Buick's lease penetration hovered around 15%. That's below the industry average of around 22% and far lower than the brands Buick is targeting, such as Acura, Lincoln and Infiniti, whose lease penetrations range from 35% to higher than half of sales.