GM has remade its once languishing Buick brand. Buick's portfolio has five vehicles, all introduced in the past two years, and the average age of its buyers, once the highest in the industry, has fallen dramatically. Buick sales rose 11% in the first quarter. Selling the bulk of its cars in China enables the brand to innovate in the U.S.and to be, in the words of its sales manager, "a brand that can afford to smile." Meanwhile, sister brand GMC is introducing a new mid-sized pickup truck to fill that market niche that has suffered from the discontinuation of the Ford Ranger.