The market diffusion of plug-in electric vehicles (PEVs) is a research topic which is often addressed, yet PEV market diffusion models differ in their approaches, the factors they include and results. Here, 40 market diffusion models for PEVs are compared in their scope, approach and findings to point out similarities or differences and make recommendations for future improvements in modeling in this field. Important input factors for the US are the purchase price and operating costs, while for Germany energy prices and the charging infrastructure are mentioned more often. Furthermore, larger sales shares of plug-in hybrid electric vehicles than battery electric vehicles are often found in the short term results (until 2030) while the picture is not so clear for the medium- to long-term. Future market penetration models should include specific PEV features like the limited range of battery electric vehicles or access to charging infrastructure, which are currently not covered by many models. Also, the integration of current policy regulations and, if possible, indirect policy incentives would enhance research in this field.