As cars get more efficient, their owners spend less money on fuel. That's good for their wallets and for the environment, but not so good for the nation's infrastructure.
That's because road maintenance is heavily reliant on revenue from gas taxes, and that revenue is shrinking as cars use less fuel--and those that run on grid electricity use none at all.
This has led some states to levy a tax on electric cars, but Oregon is pioneering a more comprehensive solution.
It's looking into whether gas taxes can be replaced by a per-mile road-use fee for all cars.
Nissan Leaf electric car at Crater Lake, Oregon [image: C. Bonville Photography]
The state is looking to institute the nation's first per-mile road tax, with the help of a data-gathering system, according to Automotive News (subscription required).
The new taxing system will be tested with a pilot program including up to 5,000 volunteer drivers that begins July 1.
They'll help decide whether a 1.5-cent-per-mile road tax can really replace the traditional gas tax.
Each car in the test will be equipped with a device that plugs into the onboard diagnostic (OBD II) port to gather mileage data.
2015 Mitsubishi Mirage
This will be overseen by road-tolling company Sanef ITS Technologies America, and its parent Intelligent Mechatronic Systems, which makes the devices.
Drivers will still pay the gas tax, but at the end of each month data will be passed on to the Oregon Department of Transportation, which oversees that tax revenue.
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The agency will compare fuel consumption and mileage data. Participants will then receive either a rebate, or an invoice for any road tax due.
Oregon previously tested per-mile road-use taxing with a smaller, 88-participant program in 2012 and 2013. The state legislature passed a bill authorizing the creation of a larger-scale mileage-based system in 2013.
2015 Toyota Prius Liftback
More than 10 states are in the process of writing similar legislation or beginning trial runs of their own systems, Intelligent Mechatronic Systems claims.
Compared to flat taxes on electric cars, measuring road use helps ensure plug-in and internal-combustion cars are charged on an equal basis.
It also accounts for hybrids, whose drivers still buy some fuel, but significantly less than with standard internal-combustion cars.
However, the Oregon system does not include out-of-state drivers, and could possibly raise privacy concerns over the onboard mileage-tracking devices.