Super-premium fuel will undoubtedly be more expensive, explaining the industry's apparent reluctance to publicly highlight such initiatives.

Automakers are reportedly preparing engines designed to run on gasoline with higher octane ratings than US drivers typically find at the pump.

The Environmental Protection Agency last year hinted that new regulations could mandate higher octane levels to help reduce emissions. Increased octane levels would allow engines to run with higher compression ratios, increasing power output relative to engine displacement.

The automotive industry has been reluctant to publicly discuss such strategies, but a Detroit Free Press report suggests companies are quietly increasing development resources in powertrains that will need to run on higher octane gasoline to achieve tighter fuel efficiency regulations. The silence is blamed on paranoia of negative consumer sentiment if an automaker is viewed as a proponent of higher octane gas, which will be more expensive than current fuel.

"Ten cents a gallon more is probably palatable," an anonymous executive said. "A quarter risks customer acceptance."

General Motors' director of global propulsion labs, David Brooks, recently said that 114 octane would be perfect for powertrain engineers. He admitted, however, that its higher cost is unlikely to be viable for the industry. Such octane levels are currently limited to racing fuel.

Automakers and the oil industry are unlikely to put their cards on the table until the next decade, potentially ahead of the tighter CAFE mpg standards that are scheduled to arrive in 2025.