Chevrolet Equinox SS/hybrid spied

Spy photographers in Michigan snapped pictures of a mysterious Chevrolet Equinox mule in testing. It's not clear what's being tested here, but it appears to be a new powertrain of some description. The most popular theory is that GM is testing a hybrid drive system for the Eqinox. Others believe the car is an Equinox SS prototype or a diesel model. We'll keep you posted as this story develops...