From http://Slashdot.org

Roland Piquepaille writes "As you might know, I enjoy big numbers. So it's just natural that I was attracted by this news release from the University of Utah, "Bad Mileage: 98 tons of plants per gallon." "A staggering 98 tons of prehistoric, buried plant material is required to produce each gallon of gasoline we burn in our cars, SUVs, trucks and other vehicles." For a reasonably efficient car, riding 25 miles per gallon, this translates to 4 tons of prehistoric plants per mile, or more than two tons per kilometer. The research paper also mentions that everyday, we are using the fossil fuel equivalent of all the plants growing during a whole year just for our cars. Even if these numbers are too large, this still makes you think about how inefficient our cars are. This analysis describes the calculations and contains other details about the research paper which will be published in November by Climate Change."