The U.S. Department of Energy and the U.S. Environmental Protection Agency have a good online guide to help consumers choose more fuel efficient vehicles. Want to read what they’re saying about E85, flex-fuel vehicles (FFV) and biodiesel? Check out www.fueleconomy.gov .
This Website has a very cool FFV Cost Calculator that allows you to plug in the type of FFV that interests you and the state in which you live. Once you’ve done this, you can see how much it would cost to drive the particular FFV fueled with E85 (with an average annual mileage of 15,000 miles).
In Wisconsin, for example, it would currently cost about $3,050 to drive a Ford F-150 FFV 15,000 miles per year. The cost to drive this truck fueled with E85 would currently be about $645 more per year than if it were fueled with gasoline. However, the calculator also indicates that one would reduce gasoline use by 730 gallons per year and reduce greenhouse gases by nearly 4,349 pounds per year. If gasoline prices increase this summer, as they surely will, you might want to check out the calculator for the most up-to-date figures.
FuelEconomy.gov also lists the advantages and disadvantages of biodiesel compared to petroleum diesel. B2 and B5 can be used safely in most engines, but as the Website points out, most vehicle manufacturers don’t recommend using blends greater than B5.
There isn’t a cost calculator for biodiesel as there is for E85 on this Website, but there is a link to diesel vehicles (several model years) showing estimated MPG and estimated annual fuel costs. You can pick up to four models at a time to compare costs.
If you’re in the market for a new vehicle, www.fueleconomy.gov  is a pretty cool tool.