Several states, including Oregon, Washington, Ohio, Pennsylvania, Florida, and Texas are studying the feasibility of the transition and what infrastructure and technology would be needed to plan for a VMT tax. In 2001, Oregon DOT (ODOT) launched a study called the the Oregon Mileage Fee Concept (PDF ), and in April of 2006, ODOT tested GPS systems in vehicles  belonging to several hundred volunteers. Based on those findings, Oregon governor Theodore R. Kulongoski this year called for outfitting every Oregon vehicle  with a GPS device that would assess a tax at the pump based on how many miles had been driven, regardless of the fuel efficiency of the vehicle.
In California last month, Assembly member Nancy Skinner  of Alameda and Contra Costa counties introduced AB 1135 , which would require every motorist to report their odometer reading when they register or renew their vehicle. The state DMV would provide overall VMT data publicly. It would theoretically be available through fairly specific tracts to aid planning, though whether it would be by block face, census tract, voter district, or county has yet to be determined.
As the bill points out, accurate VMT data is essential not only for immediate compliance with the greenhouse gas reductions mandated in AB 32, but also for smarter regional planning and the reduction of sprawl mandated in SB 375:
More accurate data about vehicle-miles-traveled--the mileage driven annually by Californians--would provide essential information to guide local transportation and land use planning. Location of transit corridor improvements, light rail, bicycle paths, and high-occupancy freeway lanes now depend on the estimates done by various state agencies, but all of these projects would benefit from more accurate data. Better data would also provide more consistent local and statewide estimates for transportation planning, city planning, and air quality planning efforts. The data would be essential in establishing long-term, historical trends in vehicle use, traffic congestion, energy consumption, and air quality measures, including ozone precursor pollutants and greenhouse gases.
One criticism of moving to a VMT tax from a gas tax is that the person
who purchased a more fuel efficient vehicle shouldn't have to pay the same as
the person who still drives a big SUV. By that logic, if a consumer
wants to drive a vehicle that pollutes more, they need to pay more at the pump.
Carli Paine, TransForm's Transportation Program Director, said that line of reasoning was flawed. "Even people who drive highly economical vehicles have an impact on the roadways and ought to pay their share for upkeep. A Prius contributes to traffic congestion just like a Mustang, but is paying less into the account that addresses congestion and roadway wear and tear."
Paine argued that odometer reporting would likely not be the final method used for monitoring VMT, but that the bill would allow planners to set targets to promote transit-oriented development (TOD) and smart growth. She said that living in close proximity to one's place of work cuts down on emissions and fuel consumption better than any vehicle technology can.
"It's hard to see how we can be serious about setting regional targets for reducing driving, without knowing how much driving is really taking place. This bill would provide a significant boost to our efforts to curb global warming pollution associated with driving and land use."
Paine suggested that a Hummer driver living within a short distance of work would use less gas than a Prius driver who commuted 120 miles each way, as illustrated in this graph:
Another criticism of altering the gas tax to a VMT tax centers on the concern that government would know too much about individual driving patterns if every vehicle had GPS or other tracking technology. Those critics have complained that placing GPS in vehicles to collect VMT data, or even self-reporting of odometer information, would violate privacy rights, though AB 1135 explicitly states that personal information would not be public record.
In a recent Metropolitan Transportation Commission (MTC) meeting, several commissioners brought up privacy concerns. MTC Executive Director Steve Heminger explained that a good deal of information is already collected through routine smog checks, self-reporting to insurance companies, and Fast Trak and Translink monitoring, etc.
MTC spokesperson Randy Rentschler said at the same meeting that "to some extent, this is an imposition on motorists, but we have to get a good sense of how many vehicle miles traveled we have... as [transportation] is the biggest source of CO2 in the state. FasTrak and Translink have privacy issues, but those databases exist. When we are given subpoenas by the police, that's the only time that we will release private data."
MTC Commissioner and Berkeley Mayor Tom Bates said: "The privacy issue is important, but the information is necessary and needed to plan and make future decisions. I think this is an important bill because we need to get VMT and the methods that we use now are so complicated and arcane. We make assumptions about the impacts of TOD; now we could actually start verifying these things."
The MTC Commission endorsed the legislation at their March meeting. Commissioners Spring and Worth were the only two members who voted against it, citing privacy concerns. Scuttlebut in the hall suggested they understood this was the first step toward a VMT tax and they were positioning themselves against the bill to please their suburban driving constituents.