Conventional Transportation Fuels

Phase II, which began in 2000, required RFG to further reduce hydrocarbon and toxic emissions. Phase II is expected to reduce smog-forming pollutants 27 percent more than conventional gasoline.

The 1990 Clean Air Act amendments also mandated the sale of RFG in U.S. cities with the highest levels of ground-level ozone pollution. Currently, RFG must be sold in 15 states.  Other areas have voluntarily opted to use RFG.  In Texas, RFG is sold in the Houston-Galveston and Dallas-Fort Worth areas.

As with clean diesel, the state of Texas classifies RFG as an alternative fuel if it can be shown to meet low-emission vehicle standards. Some other states do not recognize RFG as different enough from conventional gasoline to qualify as an alternative fuel.