All eyes are on the Netherland's fee-per-mile trials, with the program's ability to ease traffic congestion and reduce emissions under close watch. Some Dutch drivers participating in the trial have their vehicle outfitted with a meter that displays the charges for every mile driven. The meters use a "mileage-based formula that also takes account of a car's fuel efficiency, the time of day and the route," according to the New York Times. The meters, which are wirelessly linked to the Internet, can vary the fee based on traffic congestion and greenhouse gas emissions where one is driving, with charges shooting up if the vehicle is using well-traveled roads.
Supporters of the meters point out that using them actually leads to a "more equitable" system than taxes currently in place (registration fees and road-use tax) in the Netherlands. Since the meters measure exactly how much a person drives, charges vary significantly. Of course, simply having the meter in your vehicle creates quite a psychological effect. When the fees start to rack up, most trial drivers in the Netherlands realize that changes in commuting habits must be made.
Similar mileage taxes have been discussed in the U.S., with Department of Transportation Secretary Ray LaHood floating the idea back in 2009 – it dropped back to the ground in a hurry. A more successful test program took place in Oregon, but we're still a long ways from implementing any such thing on a national level here.