What is California's CARB reformulated gasoline?

What it is

The California Air Resources Board (CARB) sets a state-specific gasoline specification, currently in its third generation as CARB Phase 3 or CARFG3. The blend has stricter limits than federal-grade gasoline on:

• Reid Vapor Pressure (RVP), to reduce evaporative emissions
• Sulfur content, to enable better catalytic converter performance
• Benzene, a regulated toxic compound
• Olefins and aromatics, regulated for ozone formation
• Distillation points (T50 and T90), for combustion characteristics
• Oxygenate composition, with mandatory ethanol blending

The recipe is intended to reduce smog-forming volatile organic compound (VOC) emissions and other tailpipe pollutants in California, which has historically faced the country's worst urban air-quality challenges in cities like Los Angeles, the San Joaquin Valley, and parts of the San Francisco Bay Area.

What it costs drivers

The direct production-cost premium for CARB-spec gasoline is relatively modest at about 10 cents per gallon, based on UC Berkeley research and industry estimates. The larger consequence is what economists call supply isolation. A refinery in Texas or Louisiana that produces federal-grade gasoline cannot legally sell its product into California unless it also produces CARB-compliant fuel. Most non-California refineries do not, because California's market is smaller than the rest of the country and the additional compliance investment is significant. As a result, California is supplied almost exclusively by refineries inside the state, and when a California refinery goes offline (for maintenance, fire, conversion to renewable diesel, or closure), there is no quick way to replace the lost supply from elsewhere.

How it shapes California gas prices

The CARB indicator in our regression analysis absorbs approximately $0.44 per gallon of California's price premium over the national baseline. About 10 cents of that is the direct production cost of the blend. The remaining 34 cents is what UC Berkeley economist Severin Borenstein has called the Mystery Gasoline Surcharge: a downstream market-structure premium that emerged in 2015 after a refinery fire and has persisted despite normal supply conditions returning. The surcharge reflects California's concentrated refining sector (just over a dozen refineries serve the entire state) and unusual brand-station contracting that limits retail competition.

History

California's reformulated gasoline program is the oldest such state-level program in the country. CARB introduced the first phase in 1992 to combat severe smog problems in Southern California. Phase 2 followed in 1996 with stricter limits, and Phase 3 took effect in 2003. The 2009 reformulation tightened oxygenate requirements and eliminated MTBE, requiring ethanol blending. CARB Phase 3 has remained the operative specification since.

How it relates to federal RFG

The federal Reformulated Gasoline (RFG) program, administered by the EPA, requires a similar but less stringent cleaner-burning gasoline blend in certain metropolitan ozone non-attainment areas, including parts of California. The federal RFG blend is required in Los Angeles and the San Francisco Bay Area regardless of California's separate CARB requirement. In practice, California refineries produce CARB-spec fuel that also meets federal RFG requirements, so the two programs overlap in California rather than stack.

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