I'm trying to investigate the impact of different fleet types in the vehicle routing problem. To be precise, I'm trying to check whether a fleet of small vehicles is more efficient that a fleet of large vehicles.
There is a lot of research about Capacitated Vehicle Routing Problem (CVRP), Heterogeneous Fleet Vehicle Routing Problem (HFVRP), Mixed Fleet Vehicle Routing Problem (MFVRP) but none of those studies the impact of the different fleets.
Is there any literature about this kind of problem?