Animated line drawing of a man pushing a boulder up a hill. "Why change? Why push? Why grow? Why dream?... Never say it can't be done." Barack Obama decided to buy national ad time during the Super Bowl? No, the spot is for the GMC Yukon hybrid. The ad doesn't make an overtly environmental case for the hybrid, instead making buying one sound, bizarrely, like a brave act of personal growth. Also, can't your Yukon just tow the damn rock up the mountain?