The Environmental Protection Agency (EPA) is adopting a new statutory interpretation and making corresponding regulatory changes to allow gasoline blended with up to 15 percent ethanol to take advantage of the 1-pound per square inch (psi) Reid Vapor Pressure (RVP) waiver afforded under the Clean Air Act (CAA). In doing so, EPA is finalizing an interpretive rulemaking which defines gasoline blended with up to 15 percent ethanol as "substantially similar" to the fuel used to certify Tier 3 motor vehicles. Finally, EPA is making regulatory changes to modify certain elements of the Renewable Fuel Standard (RFS) compliance system, in order to improve functioning of the renewable identification number (RIN) market and prevent market manipulation.