Hybrids are for environmentalists. Big SUVs are for people who don’t care about spotted owls. At least, those are the stereotypes. However, GM is mixing these two with what could turn out to be the biggest hybrid advancement yet, and we’re not just talking about sheer size. No, the real story here is that improving the mileage of a gas guzzler may well have a larger impact on the environment than improving the efficiency of already-thrifty cars. With 332 horsepower, a 6,200-lb. tow capacity, and the ability to go full-electric under 30 mph, the GM twins could very well be game changers.