The Variable Displacement Supercharger (VDS) is a twin helical screw style compressor that has a feature to change its displacement and its compression ratio actively during vehicle operation. This device can reduce the parasitic losses associated with supercharging and improve the relative fuel economy of a supercharged engine.Supercharging is a boosting choice with several advantages over turbocharging. There is fast pressure delivery to the engine intake manifold for fast engine torque response providing the fun to drive feel. The performance delivered by a supercharger can enable engine fuel economy actions to include engine downsizing and downspeeding. The cost and difficulty of engineering hot exhaust components is eliminated when using only an air side compressor. Faster catalyst warm up can be achieved when not warming the turbine housing of a turbocharger.To quantify these effects, a 2.0L Ford Eco-Boost® engine was chosen for an analytical comparison of three boosting configurations: turbocharged, roots style supercharged, and twin screw compressor supercharged with variable displacement. A number of partial load points were chosen to compare cycle averaged fuel consumption of the boost systems with weighting factors that represent a large SUV. Engine dynamometer testing validated the simulation results.