Mercedes has jumped in the Hybrid game along with everyone else, and this is probably the totally right line to do it with... the ML.   Delivering the ML 450Hybrid will allow folks to help increase the fuel efficiencies of a typical gas guzzler to  getting between 21-24 mph.   This is great for this size and weight of a truck.  I own a GL450, and while we get decent mileage at 17-19 mpg, that extra 5mpg would be certainly appreciated.   The gas side of the operation relies on efficient Mercedes Mass Air Flow Sensor and Mercedes Fuel Injectors to deliver the power when needed and an ultra sophisticated system to regain energy and redeliver it as electric power.