California drivers could eventually face a new kind of road tax that charges them for every mile behind the wheel — and they may not need to have their location tracked to pay up.

The proposal got fresh attention this week after gubernatorial hopeful Xavier Becerra refused to rule out a mileage tax, saying “everything was on the table” during an interview.

Becerra’s campaign later clarified that he had not actually proposed the tax, but his comments raised a big question for millions of California motorists: How would Sacramento know how far they’re driving — and would the state be tracking their every move?

A six-month California pilot program offers a glimpse of how it could work, including options ranging from GPS-equipped tracking devices to something as simple as snapping a picture of a car’s odometer.

The experiment, conducted by Caltrans from August 2024 through January 2025, enrolled 800 participants who tested four different ways of reporting their mileage.

Drivers could plug a GPS-enabled device into their vehicles, use a device without GPS, allow their car’s built-in technology to transmit mileage data or simply upload photographs of their odometers.

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Location sharing was optional, meaning drivers could participate without handing over a record of where they traveled.

About 34% of participants chose GPS-equipped devices, while 30% opted to submit odometer photos. The remaining drivers used onboard vehicle technology or devices without GPS.

The pilot also tested what drivers might actually pay.

Half of the participants were charged a flat rate of 2.8 cents per mile, meaning someone driving 10,000 miles would owe $280 before credits. The other half faced individualized rates based on their vehicles’ federally rated fuel efficiency.

Drivers received monthly bills but were credited or refunded for state gas taxes or the electric-vehicle Road Improvement Fee they had already paid during the experiment. 

The experiment grew out of Senate Bill 339, authored by state Sen. Scott Wiener (D-San Francisco) and signed by Gov. Gavin Newsom in September 2021. The legislation directed California to test ways of collecting road charges based on actual mileage as traditional gas-tax revenue declines.

But the possibility of another bill hitting drivers’ wallets has already sparked a political fight.

Republican gubernatorial rival Steve Hilton has pledged to veto a mileage tax if elected.

“They never stop gouging you,” Hilton told The California Post.

Assembly Republican leader Alexandra Macedo also blasted the idea, arguing it would disproportionately hurt 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, no statewide mileage tax has been approved.