Diesel vehicles are meta-efficient when run with Biodiesel fuel. Some cars are listed as "TDIs", meaning they have a Turbo-Charge Direct Injection Engine — these cars can also be run on Biodiesel. Diesel engines are fuel-efficient, for example VW Jetta TDIs get around 47 mpg. Earlier diesel cars, produced in the 1960s and 1970s were… [Continue Reading]