Here's proof that GM is serious about hybrid versions of its largest SUVs: photos of hybrid Tahoes and Yukons undergoing hot-weather testing this past summer. Details are scant after that, but it's encouraging that the prototypes were seen hauling trailers. Rumors have abounded that trailer-towing with a hybrid is a challenge that's even bamboozled Toyota.
Details about the makeup of GM's hybrid drivetrains are nonexistent, so go ahead and speculate. However, these will be true hybrids capable of running solely on batteries and not the semi-hybrid system used on some GM pickups. Expect hybrid Chevrolet Tahoes, GMC Yukons, and Cadillac Escalades to go on sale later this year as 2008 models.