Carpooling, higher fuel economy, hybrids and electric cars may be good for the environment, but they're bad for government transportation funding, which relies on gasoline and diesel taxes.
Now some states, including Vermont, are mapping out a possible alternative: taxing drivers not based on how much fuel is burned but how far each vehicle travels.
Vermont Transportation Secretary Brian Searles says such a system — probably five years off at least — would use GPS devices to track mileage and then levy a tax on a per-mile basis.
Officials in other states say there are other technological approaches that wouldn't raise the privacy issues of GPS tracking. An Oregon bill would let motorists choose from a range of technologies.