This paper contains an evaluation of the environmental performance of a comprehensive set of current and future mid-size passenger vehicles. We present a comparative Life Cycle Assessment (LCA) based on a novel integrated vehicle simulation framework, which allows for consistency in vehicle parameter settings and consideration of future technological progress. Conventional and hybrid gasoline, diesel and natural gas cars as well as battery and fuel cell electric vehicles (BEV and FCV) are analyzed, taking into account electricity and hydrogen production chains from fossil, nuclear and renewable energy resources. Our results show that a substantial mitigation of climate change can be obtained with electric passenger vehicles, provided that non-fossil energy resources are used for electricity and hydrogen production. However, in terms of other environmental burdens such as acidification, particulate matter formation, and toxicity, BEV may in some cases and FCV are likely to perform worse than modern fossil fueled cars as a consequence of emissions along vehicle and fuel production chains. Therefore, the electrification of road transportation should be accompanied by an integration of life cycle management in vehicle manufacturing chains as well as energy and transport policies in order to counter potential environmental drawbacks.