Critics of Oregon's plan have additional complaints: They say a VMT does not incentivize people to drive greener cars the way a gas tax does, and it doesn't discourage the use of big vehicles that tread more heavily on the highways.
"Dealing with climate change is not a top priority of Oregon's transportation planners," said Steve Woolpert, professor of politics at Saint Mary's College of California.
Some view the VMT as a means of addressing an unfairness in the system as people opt for more fuel-efficient vehicles—for example, that Prius drivers end up paying less for road infrastructure than their gas-guzzling counterparts. Woolpert thinks that's a wrongheaded argument. "(VMT) will weaken incentives for buying fuel-efficient vehicles. … It is unfortunate that Oregon is pursuing a VMT rather than a comprehensive response to climate change."
But Whitty said that those who think Prius drivers should pay less for road infrastructure are missing the point. "Every motor vehicle demands that the road be in shape when it leaves the driveway," he said. He added that while the 5,000-volunteer deployment of the road-usage charge is open to all vehicles regardless of fuel-efficiency, a broader road-usage tax deployment "would likely only apply to fuel-efficient vehicles," while gas guzzlers would be stuck with the gas tax.
(Read more: This could be Exxon Mobil's biggest threat)
Privacy advocates have also voiced concerns. The default measurement device will use GPS, and in America's post-Snowden era, many are skittish about handing the government even more tracking data, even if the state promises it will be destroyed after 30 days. As a workaround, the plan allows for simply paying a flat tax or measuring miles traveled by odometer readings.
Of course, that's hardly foolproof when some 452,000 used cars are sold in the U.S. with falsified odometer readings each year, according to a National Highway Traffic Safety Administration study.
"There's a possibility of fraud with any hardware solution," said Zahn.
But Whitty pointed out that the reading is not of the manufacturer-installed odometer, but an auxiliary device that plugs into a car's diagnostic port and delivers data gathered from wireless—presumably harder to tamper with.
1919 all over again?
Zahn said the self-selective nature of the 5,000-person deployment is problematic as a template for any larger scheme in the future: It's most likely to attract people who have done the math and who see it as being economically advantageous for their particular vehicle and driving habits. It's also unlikely to attract a representative number of people bent on defrauding the system.
Baker says he thinks odds are very good other states will test systems like VMT—the need to address infrastructure funding shortfalls is just too urgent.
Zahn sees the system's costs and politics as roadblocks. "I think it's a long way off before you'd see something that is recognized nationally," he said. Between the cost of tracking devices, fraud detection and enforcement, Zahn questioned, "Can they really reach their goal of broadening the tax base?"
But skeptics of Oregon's scheme may want to note that this isn't the first time the Beaver State has blazed a taxation trail: In 1919 it was the first state to tax gasoline by the gallon.
Within a decade, all other states had followed suit.
—By Matt Twomey, Special to CNBC.com
Follow him on Twitter @Matt_Twomey