The 2014 power & gas retailers' benchmark study of European incumbents found that there is a significant difference in costs per customer between the best and worst performers, with a difference of 35€ being common. The study also found that economies of scale are relevant for retailers, particularly in the most massive segments. However, it is important to note that having an efficient operation is also essential in the residential segment, where the underlying demand growth is modest or non-existent. The study's conclusions highlight the need for power & gas retailers to improve their costs and operations in order to drive their business forward.