more power per unit of displacement than their gasoline counterparts. Examples of octane mis-citation can be found at the Iowa Renewable Fuels Association titled "E85 Facts" which cites a range of 100-105, and a document at the Texas State Energy Conservation Office titled "Ethanol", which cites a 113 rating. Some vehicles can be converted to use E85 despite not being specifically built for it. Because of the lower heating value E85 has a cooler intake charge—which, coupled with its high stability level from its high octane rating—has also been used as a "power adder" in turbocharged performance vehicles. These modifications have not only resulted in lower GHG emissions, but typically resulted in 10-12% power and torque increase at the wheels. Where the engine was previously knock limited by gasoline, power improvements are as high as 40%. Because of its low price (less than US$4.00/gal in some places) and high availability in certain areas people have started to turn to using it in place of high-end racing fuels, which typically cost over US$10.00/gal. Emissions There are four primary types of pollutants scientists study. These emissions are hydrocarbons (HC), oxides of nitrogen (NOx), carbon monoxide (CO) and carbon dioxide (CO2). Because E85 is predominantly ethanol, the exhaust emissions are very different from those of regular gasoline. Numerous studies have compared and contrasted the different emissions and the effects these emissions have on the environment, but the tests have been inconclusive. The tests have shown very little consistency if any at all because there are too many variables involved. The make and model of the vehicle, the way in which the ethanol was produced and the vehicle's overall fuel efficiency all play a large role in the overall outcome of each study. To address the problem of inaccuracy, engineers at the National Renewable Energy Laboratory combined data from all applicable emissions studies and compiled them into one data set. This compiled set of data showed that on average all emissions that are federally regulated showed a decrease or no statistically relevant difference between E85 and gasoline. EPA's stringent tier-II vehicle emission standards require that FFVs achieve the same low emissions level regardless whether E85 or gasoline is used. However, E85 can further reduce emissions of certain pollutants as compared to conventional gasoline or lower-volume ethanol blends. For example, E85 is less volatile than gasoline or low-volume ethanol blends, which results in fewer evaporative