This book highlights ways of using gaseous and liquid e-fuels like hydrogen (H₂), methane (CH₄), methanol (CH₃OH), DME (CH₃-O-CH₃), Ammonia (NH₃), synthetic petrol and diesel, etc in existing engines and their effects on tailpipe emissions. The contents also cover calibration and optimization procedure for adaptation of these fuels. the volume also discusses the economical aspect of these fuels. Chapters include recent results and are focused on current trends of automotive sector. This book will be of interest to those in academia and industry involved in fuels, IC engines, engine instrumentation, and environmental research.