The Authors have analyzed the energy behavior of the machine tool park in energy workshop belonging to an Italian automotive industry. This analysis showed that a large amount of electric energy is wasted owing to an irrational machine tool use. A mathematical model was formulated, to demonstrate - and subsequent experimental tests confirmed the model results - that by simple management measures, which don't require transformations in the existing machinery, it is possible to save more than 10% of the electric energy absorbed by the machinery itself, the productivity being unchanged.