A driving style evaluation system (1) for a motor vehicle (2), configured to receive and process motor vehicle-related data and motor vehicle mission-related data to compute a Driving Style Evaluation Index (DSEI) indicative of the driving style of a motor vehicle driver during a motor vehicle mission in relation to a motor vehicle fuel consumption, based on the following summary index: Fuel Economy Index (FEI), which is indicative of the driving style of the motor vehicle driver from the fuel saving perspective, and is computed based on pre-summary indices computed based on respective partial indices in turn computed based on a combination of the following physical quantities which affect the motor vehicle fuel consumption: time interval, ending with a motor vehicle stop, during which the motor vehicle speed reduction is mainly due to a combination of a gas pedal release and a gear downshift, possibly with operation of at least one motor vehicle braking system only during the final part of the maneuver; engine speed and torque fluctuations within preset time intervals; time elapsed between a gas pedal release and operation of at least one motor vehicle braking system; time during which at least one motor vehicle braking system is operated; amount of energy dissipated by at least one motor vehicle braking system; engine power and instantaneous fuel consumption in different gears; and time interval between two consecutive gear shifts; and wherein the pre-summary and partial indices are weighted by means of respective dynamic weighting coefficients, each of which is computed based on a respective motor vehicle mission-independent weight, which is indicative of the influence that the physical quantities based on the which the Fuel Economy Index (FEI) is computed have on the overall fuel consumption reduction, and based on a respective motor vehicle mission-dependent benefit, which represents an evaluation of the benefit that the Fuel Economy Index (FEI) provides in the driving style evaluation during the motor vehicle mission.