California motorists could eventually face a road-use charge based on every mile they drive, but paying the fee may not require the state to track their location.
The proposal drew renewed attention this week after gubernatorial candidate Xavier Becerra declined to rule out a mileage tax, saying “everything was on the table” in an interview.
Becerra’s campaign later said he had not proposed such a tax. Still, his remarks left millions of California drivers wondering how Sacramento would measure their mileage — and whether participating motorists would have to surrender a detailed record of where they travel.
A six-month California road-charge pilot provides a preview of how a mileage-based system could operate. The options tested ranged from GPS-equipped devices to the most basic approach: taking a photograph of a vehicle’s odometer.
Caltrans conducted the pilot from August 2024 through January 2025, enrolling 800 participants to evaluate four different methods for reporting vehicle mileage.
Participants could connect a GPS-enabled device to their vehicles, use a device without GPS, permit their cars’ built-in technology to transmit mileage data or upload odometer photographs.
Sharing location data was optional, allowing drivers to take part without providing a trip-by-trip record of where they had been.
Roughly 34% of participants selected GPS-enabled devices, while 30% chose to submit odometer photos. The rest relied on onboard vehicle systems or non-GPS devices.
The pilot also examined how much drivers might owe under a mileage-based road fee.
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Half of the participants were assessed a flat 2.8 cents per mile. At 10,000 miles, that would amount to $280 before credits. The others were assigned personalized rates tied to their vehicles’ federally rated fuel efficiency.
Participants received monthly statements, along with credits or refunds for state gas taxes or the electric-vehicle Road Improvement Fee they had paid during the pilot.
The test program was created under Senate Bill 339, authored by state Sen. Scott Wiener (D-San Francisco) and signed by Gov. Gavin Newsom in September 2021. The law called for California to study mileage-based road charges as revenue from the traditional gas tax continues to decline.
Even so, the prospect of adding another charge for drivers has quickly become a political flashpoint.
Republican gubernatorial candidate Steve Hilton has promised to veto a mileage tax if he wins election.
“They never stop gouging you,” Hilton told The California Post.
Assembly Republican leader Alexandra Macedo likewise criticized the proposal, saying it could place a disproportionate burden on working Californians.
“They say they want to tax billionaires and then they’re talking about a mileage tax that hits the working class the hardest,” she told The Post.
For now, California has not approved a statewide mileage tax.
