This paper presents a novel local trajectory planner designed for autonomous off-road vehicles operating on rugged terrain at high speeds. The approach addresses critical safety challenges by developing a Model Predictive Control formulation with a new dynamics model specifically tailored for non-planar terrain. A key innovation is the energy-based constraint that enables safe extreme mobility scenarios, including tire liftoff without rollover, while preventing rollover events that current methods fail to mitigate. Real-time feasibility is achieved through parallelized GPGPU computation, allowing the system to perform complex trajectory optimization within operational time constraints. The planner's effectiveness is validated through both simulation and full-scale physical experiments, demonstrating safe and extreme trajectory generation for autonomous off-road vehicles.