The actual fuel used by the IRL is a blend of about 98 percent ethanol and 2 percent denaturant. The exact composition includes a small amount of high-octane racing fuel. The fuel for today's Indy cars has an octane rating of 113, compared with methanol's 107. This means a significant reduction in pre-ignition, or knocking and pinging. In addition, many of the people who handle the fuel, say it smells like tequila.