CARBOB is the standard grade of gasoline supplied to the California market.

CARB (California Air Resources Board) is the state regulatory agency that set the quality standards for gasoline in California.

CARB gasoline is supplied as a BOB (Before oxygenate blending) grade because it is blended with 10% ethanol before distribution to retail stations.

The specifications for CARBOB are have been set tighter than for the rest of the US to address the particularly acute air quality situation in California.