zarathud writes: The News&Observer reports that the U.S government and 15 states have commissioned a trial of a satellite-based vehicle tracking system. The intent of the system is to monitor highway use in order to tax it. Participants will have "GPS computers" mounted in their cars and receive mock state and federal tax bills for their mileage. The justification for the proposed tax is that alternative energy cars sidestep the gas taxes that help fund roads. This system appears to be quite different from the tracking system Slashdot covered last month. This idea has been considered by Oregon and California before. Economist Mike Moffatt has a few criticisms.