Using the functional series of transportation energy efficiency estimates based on the Bartini’s LmT-4-Table entities, the author developed a method to assess sections of combined transportation according to the criterion of energy consumption with account for the squared speed of freight movement. The possibility of comparing values of specific energy consumption for different transport modes is evaluated. The results of the comparison make it possible to identify weak points of combined transportation as well as starting points for transportation plan improvement. A numerical analysis is carried out using an illustrative example of combined transportation involving container ships, automobile and railway transport. Modeling and calculation are carried out using the EcoTransIT calculator within the well-to-wheel boundaries. The author provides recommendations on further extension of the concept and introduction of energy efficiency index into the transport service life cycle assessment (LCA) methodologies.