The two alternate suspension modes, Sport and GS, each make the damper settings a smidge more aggressive than standard mode. According to Buick, sport mode is about 20 percent stiffer than normal. GS mode is yet another 20 percent stiffer than Sport, and also increases steering effort. That added steering feel made GS the default mode for us whenever spirited driving was called for. As such, we found little use for the mid-level suspension setting.
Plus, hitting the GS button changes the gauge backlighting from blue to red -- so why ever settle for plain, old Sport mode? We're not saying that color-changing gauges play any part in the GS' performance recipe, but boy, do they look cool.