Autonomous ground vehicles operating in the field are likely to be faced with several mobility challenges such as piles of rubble, water crossings, steep hills, mud, and stiff vegetation patches. These scenarios are particularly critical for smaller robots with torque and power limited actuators, which as experimentally shown in this work can easily fail to accomplish their tasks in these environments. This paper motivates and provides a methodology that integrates the robot, actuator and terrain models with an efficient motion planner to exploit the vehicle momentum as a way to successfully traverse these difficult terrains. In particular, experimental results showing the efficacy of the proposed methodology are presented for a vegetation patch and a steep hill. Finally, a discussion of the necessary perception work to fully automate the process is included.