"Where did you demonstrate Buick is doing poorly in its domestic market? "

As I pointed out Buick only sold 259,000 vehicles in the USA in 2015, a huge 40% drop since 430,000 in 2002. That is during a period of population and economic  growth. They now only have a paltry 1.28% of the US car market. If that isn't "doing poorly" I'd hate to see what is . . .