Regulatory and market pressure to reduce greenhouse gas (GHG) emissions has directed the path of powertrain development towards expanded use of electrification. Powertrain electrification contributes to GHG reduction by lowering the demands on the engine for improved durability and efficiency and by introducing synergistic technologies such as kinetic energy recovery. This work reviews the advancement of energy-efficient hybrid powertrains with application of dual motive powers, internal combustion engine and electric motors. The focus of this review is on the industrialisation of dedicated hybrid engines (DHEs) and transmissions (DHT). Based on the DHT framework, DHEs are exemplified through those successful hybrid vehicles in the market. Technology challenges for both DHE and DHT are discussed. The key enablers of controls and model-based design are reviewed to disclose the progress of hybrid powertrain development by using both endogenous fuel and exogenous electricity if applicable. Case studies for both passenger cars and commercial vehicles are also presented
