Performance bench tests are commonly used to assess power and fuel consumption of agricultural tractors. OECD test procedure allows energetic efficiency assessment of these vehicles in order to compare them for a typical use. However, special care has to be paid on the recent tractors, where electronic control on both engine and transmission are implemented in order to facilitate driving and optimize fuel needs. In this paper, a simulation tool is proposed to link some field measurements and bench results for a predictive assessment of the fuel consumption. Force and energy balances are computed through the mechanical system starting from the operator demand to the engine characteristics. Different driving scenarios are developed to compare tractor control strategies. Sensitivity studies are performed to choose the most suitable models for engine and driving strategies in the numerical approach. Different methodologies are then used to assess fuel consumption during a spreading field operation: pollution regulation weighting, energy efficiency weighting and numerical results are compared to field records. Discussion provides some guidelines for establishing future testing procedures and presenting their results accounting for the real use of tractors.