This paper proposes an eco-efficient speed dependent model based on a realistic variant of the Vehicle Routing Problem with time windows constraints, backhauls nodes and heterogeneous fixed vehicle fleets, in which vehicles are characterized by different capacities, costs and emission factors. The tackled problem presents a more realistic objective function that accounts not just for internal costs, but also for externalities in transport activities such as CO2 emissions, pollutants emissions, noise and accidents. The EMEP/CORINAIR model equations are used for estimating fuel consumption, CO2 and pollutants emissions based on the vehicle assigned speeds. Finally, this paper presents a case study analysing the results on the choice of speed dependent eco-efficiency routes, which can help to reduce the emissions of air pollutants, noises and greenhouse gases, without losing competitiveness in transport companies.