Photos: From gas guzzler to green extreme

What makes this Chevy Suburban different from most? It runs on a hybrid engine that gets its electricity from plugging into a wall outlet. Professor Andrew Frank built it at the University of California at Davis and has tested it on GM's off-road tracks.

Plug-in hybrids use less gas and consequently can get about 100 miles per gallon. However, it will take years before they become widespread.

Photo by Andrew Frank/University of California, Davis