Earlier, the U.S. Environmental Protection Agency approved up to 15% ethanol use in all cars and light trucks 2001 and newer.
In a March 29, 2011 decision, EPA says any owner may use ANY blend of ethanol in ANY vehicle provided the following is true:
1. The vehicle must be the greater of 10 years old or more, OR the vehicle must have 120,000 miles or more, AND
2. The vehicle must pass a standard emissions test while running the alternative fuel.
The EPA states the emissions tampering rule is wavied if the above conditions are true.
The 10 year, 120,000 mile rule is due to the EPA concern that high blends ( ex. 85% or E85) MIGHT affect the catalytic converter. EPA considers 10 years or 120,000 miles the "end of useful life" for the device anyway... so they are relaxing the "tampering" rules.
Maybe this is tacit admission that ethanol is so good and clean burning that you can use it in a car with a "worn out" catalytic converter and still pass an emissions test.