Development of plug-in hybrid electric vehicles (PHEVs) is stimulated by the need to replace nonrenewable energies with sustainable and more environment-friendly new energy types. PHEVs benefit from a combination of an internal combustion engine and an electric motor with a rechargeable and larger battery pack than conventional hybrid vehicles. In order to maximise customer satisfaction and motivate replacement of the conventional vehicles with this new technology, the design of PHEVs requires sufficient differentiation in the product specifications for diverse market segments. The added set-up time, processes, costs and longer lead time for designing and manufacturing a diverse range of such vehicles is a hurdle towards increasing their diversity. This study proposes an efficient product family design (PFD) method for mass customisation of the PHEV powertrains. The methodology is less dependent on expensive simulations due to use of metamodelling and non-conventional sensitivity analysis. The PFD concept and its implications to a family of five PHEVs are investigated, and benefits as well as limitations of a sustainable development for this complex product are discussed.