If you drive a fancy car, you've probably noticed you're paying even more lately for the privilege.
The nationwide average price difference between regular and premium unleaded gasoline reached 30 cents per gallon for the first time in 2012 and has stayed at or above that level so far this year, according to data released this month from the U.S. Energy Information Administration.
The price spread has climbed steadily from 18 cents in 2000, peaking at 33 cents in January.
Regular unleaded has an octane rating of 87, while premium boasts octane levels of 91 to 93.
In Oklahoma on Thursday, premium fuel users paid on average 27 cents more per gallon than regular consumers paid, according to AAA's fuelgaugereport.com.
For cars designed for regular, there is no advantage to using the more expensive fuel. Engines that call for higher-octane fuel are more likely to knock if the octane level falls too low.
Higher-performance engines are more likely to call for the more expensive fuel. Typically those are found in sports and luxury vehicles.
The rising price of higher-octane fuel has to do with changing fuel blend processes, according to the government report.
Refiners previously used MTBE to raise octane levels, but the Energy Policy Act of 2005 banned the chemical because it was found to cause cancer when it leaked into the water supply.
Today, octane is raised primarily by adding ethanol. Most gasoline sold in the United States today is e10, which is a blend of 10 percent ethanol and 90 percent gasoline. Fuel ethanol has an average octane rating of 115.
Refiners typically produce 84-octane gasoline that is blended with ethanol to make regular, 87-octane e10, and 88-octane gas that mixes to create 91-octane e10.
There are other octane boosters, but they are more expensive. More of those costly additives are needed to boost the pre-blended fuel four more points to 88.
These expensive octane additives also are much of the reason why 100 percent gasoline without an ethanol blend tends to cost more than e10.
I am looking to replace my 15-year-old Chevy Lumina. One requirement I have in a new vehicle is that it does not have a fancy engine designed for high-octane fuel.