Buick is a huge brand in China, very profitable for GM. That might be part of the reason, also the Enclave is supposed to be doing well.
I think Buick is GM’s anti Lexus. The Enclave is selling very well. And this 2010 Lacrosse takes direct aim at Lexus ES 350.
http://a332.g.akamai.net/f/332/936/12h/www.edmunds.com//pictures/VEHICLE/2010/Buick/2010.buick.lacrosse.20274589-E.jpg