Energy consumption is a major issue for the global society. A hybrid drive train can significantly improve the energy efficiency of ground vehicles. The combination of high energy density and high power density make a flywheel hybrid system a promising option. A primary challenge of a flywheel hybrid system is coupling a high speed flywheel to a vehicle's drive train. A unique way of accomplishing this task is using a switch-mode continuously variable transmission (CVT), which is the mechanical analog of a DC-DC power electronics converter. Modeling and analysis were conducted of the major components of a full size passenger vehicle switch-mode CVT. This model was scaled down to allow for the design and manufacturing of a laboratory prototype. Experimental data taken from the prototype was used to verify proof-of-concept and quantify the nature and magnitude of system losses. The results demonstrate the correct operation of the system on a high level, but future work is required before reliable experimental data is acquired.