Biodiesel cars have some similarities and differences when compared to a diesel car. Biodiesel is a type of diesel. However, it is not the normal diesel you have seen for the past 30 years. Regular diesel is petroleum based, whereas biodiesel is made from organic materials such as corn and vegetable oils. Diesel car MPG is a big reason that people buy diesel cars, but does biodiesel have the same fuel efficiency? The answer is no, because there is much less energy in biodiesel than regular diesel. Biodiesel isn’t even as efficient as regular gasoline, and diesel is 33% more fuel-efficient than gasoline. The most common biodiesel is E85, or Ethanol 85. This means that it is comprised of 85% ethanol, and 15% gasoline. The fuel efficiency argument would be enough to get you to easily choose diesel over biodiesel. However, biodiesel has a big environmental aspect as well. Since it is made from corn and other organic materials, it is considered a renewable resource. We can pretty much grow it whenever we need it. This is the opposite of oil, since we can only use what we have, and never use it again once it is burned. Biodiesel is also much better on the environment compared to diesel. Diesel burns very dirty and releases a lot of harmful emissions into the atmosphere. Biodiesel is the exact opposite and has some of the lowest emissions for cars that run on a type of fuel. Biodiesel is cheaper than diesel, but the cost does not outweigh the fuel economy advantages of diesel.