The state Board of Equalization tracks gas sales via California's 18-cents-a-gallon excise tax. Though relatively small, the decline is significant, said agency spokeswoman Anita Gore. While drivers have grumbled about rising prices for years, they kept driving and consumption continued to rise, Gore said. People grew accustomed to the volatility of gas prices, she said. "Until the gas price rises and stays higher for a significant amount of time, we don't typically see a drop," she said.

The numbers show drivers are making changes, such as consolidating trips, car pooling and buying more fuel-efficient vehicles, she said. According to AAA spokesman Sean Comey: "Ultimately, it seems as if we've reached the point where the consumer is fed up with buying a product they think is overpriced, and they're trying to fight back." Nationally, however, gasoline demand still is rising, according to the U.S. Energy Information Administration. Part of the reason may be that prices remain lower in the rest of the nation, an average $2.99 a gallon for unleaded on Friday, according to AAA. Gas in California, which refines an environmentally friendly blend, costs more, at about $3.21 a gallon.