This paper presents the application of the Lambda control strategy derived from Pontryagin’s Minimum Principle (PMP) for parallel PHEV. The proposed method has shown its efficiency for hybrid vehicles. It is here extended to the Plug-in hybrid vehicle case where reducing fuel consumption and ensuring optimal behavior of the state of charge of the battery are the specific, focused performance benchmarks. Offline PMP application requires the knowledge of the entire drive cycle to obtain optimal control, leading to the best engine energy consumption. Online, adapting this method requires a good estimation of the weighting parameter lambda value, which is not an obvious task. A fast initial estimation-based method is presented in this paper as a starting point for an adaptive L-control. The proposed method is then evaluated using standard driving cycles and compared with offline PMP results. Robustness study is also accomplished by testing method performances using mixed cycles.