The GMC Yukon Hybrid is the counterpart to the Chevy Tahoe Hybrid. And the GMC Sierra Hybrid is the sibling to the Chevy Silverado Hybrid. GMC appears to be the only brand with an exclusive focus on fuel-sipping vehicles for people who work for a living and tow big things on the weekend. That’s great. We think there’s a strong case to be made for a line of more efficient work machines. The big question is how long General Motors will stand behind them. The Yukon and Sierra are impressive—although a bit pricey—attempts at a greener versions of the segment. But based on GM’s publicity onslaught for the Chevy Volt plug-in hybrid, it makes the GMC hybrids seem like “also-rans.” Production numbers have been low, and yet the full-size SUV and pickup traditionally are huge sellers. Let’s see if GM begins pumping up the volume.