General Motors has long used truck chassis as the foundation of its largest SUVs: the Escalades, Tahoes, and Yukons. But with fuel costs going nowhere but up and stricter fuel standards on the horizon, GM is considering switching those models to lighter car-sized underpinnings when they come up for redesign in 2012, Left Lane News reports. Is the 90’s mega-SUV a dying breed? (More SUVs stories.)