AbstractReplacing fossil fuels in the transport sector by renewable energy will help combat climate change. However, lowering greenhouse gas emissions by switching to alternative fuels or electricity can come at the expense of land and water resources. To understand the scale of this possible trade‐off, we compare and contrast carbon, land, and water footprints per driven km in midsize cars utilizing conventional gasoline, biofuels, bioelectricity, solar electricity, and solar‐based hydrogen. Results show that solar‐powered electric cars have the smallest environmental footprints per km, followed by solar‐based hydrogen cars, and that biofuel‐driven cars have the largest footprints.