Free Piston Engine: Worth Investing In It to Power Future Electric Cars?

Since the idea of economy started in humanity's mind, everybody wants to reduce the expenses, mostly on energy dependence. Nowadays, when hybrid cars and, generally, electric vehicles are starting to play a huge role in car industry, and electric technology is starting to get cheaper yearly, there still are scientists that get inspired by the old explosion engine principles, albeit they are being used for more than a hundred years and their power source is mainly based on fossil fuel.