It looks like all of GM brands saw increased sales during March. Amongst all of the brands, the largest gains were seen by Buick. By the end of the month, their sales saw a 28% increase. Buick nearly sold 6,000 more units than they did during the same period from last year. A large part of their success was thanks to the brands crossovers and SUV's, as sedans and passenger cars continue to take a hit. Last month alone Buick sold 4,367 Envisions, up 21% from last March. Here's a breakdown of the numbers.