SACRAMENTO (KRON) – Governor Gavin Newsom is demanding an investigation into big oil companies as Californians pay more for gasoline than most in the country.

While Californians spend up to 30 cents more per gallon at the pump than most other states, California’s Energy Commission claims big oil companies are partially to blame.

Earlier this year, Governor Newsom directed the agency to look into California’s “mystery surcharge” outside of the state’s taxes and fees at gas pumps.

In its report released Monday, the CEC concluded the charge could be traced to retail sales with companies like 76, Chevron and Shell overcharging in California and possibly falsely advertising premium gasoline compared to unbranded companies.

Newsom Monday requested Attorney General Xavier Becerra open an investigation.

In a letter to Becerra, the governor wrote, “the mystery surcharge adds up, especially for cost-conscious, working families. If oil companies are engaging in false advertising or price-fixing, then legal action should be taken to protect the public.”

Oil companies have not responded to the energy commission’s request for information to support their product claims.