Decision regarding the choice of aggregator for plugging in electric hybrid vehicles (PHEV) is challenging in several respects. This work introduces the concept of a best fit load line maintained by the aggregators and estimated by the plug-in vehicles based on communication regarding the plug-in status of other such vehicles. It is conceptually argued that the decision to send request to a potential aggregator should be governed by the matching between the slopes of the actual and estimated load lines of the aggregators. Simulation results based on uniform probability distribution are presented to explain the concept. © 2017 IEEE.