DETROIT -- Buick pulled off a rare feat when the lithe, sculpted Avenir concept sedan rolled onto a stage here last week: It surprised just about everybody in this loose-lipped town.
But if recent history is a guide, it would be wise to expect the unexpected from Buick's product planners. The brand's U.S. lineup -- threadbare five years ago -- has emerged as a place where General Motors can gamble on different body styles and explore market niches that its rivals either haven't yet discovered or don't care to.