After years of incentives to use less gasoline and drive more fuel-efficient vehicles -- the most effective of which may be $3+ per-gallon gasoline -- the National Governor's Association and others have come up with a way to reverse the incentives and penalize drivers who use less fuel while traveling the same amount of miles. Actually, that's not the stated intent of the measure, but it's what could happen if "tax by mile driven" measures become law. You see, fuel-efficient vehicles and ethanol are cutting into state tax revenues. So as we get green -- beginning to solve one set of problems -- the tax authorities see another problem looming -- less gas tax revenues. So they are backing a plan to tax for miles driven in addition to gasoline purchased.

What this means is that a motorcyclist or hybrid driver who gets 60 miles per gallon of fuel and commutes 60 miles per day, will pay the same amount of mileage tax as a guy driving a Cadillac Escalade or Nissan Titan 60 miles per day and getting 15 or 20 miles per gallon. So the two drivers would pay the same amount per gallon of gas, but the mileage tax incentives favor the bigger vehicle.

But there's an important question here: If the "miles driven," tax is implemented, will the gas tax disappear? Doubtful. So another way to tax the motorist arrives atop the old way. Perhaps the politicians hope that Prius drivers and Hummer owners will be arguing with each other and miss the fact that another tax has just been levied on transportation.

And there's another bad idea that merges into this traffic taxation lane. In order to do the mileage tax, motorists would need to install GPS monitoring equipment in their vehicles to keep tabs on how many miles they travel. Similar location-based systems -- called congestion pricing -- are now being tested in cities around the world. The closer the vehicle goes to the center of the city, the higher the toll paid by the vehicle owner. So instead of anonymous travel, the freedom of the road, and "hey I've got a tiny uncomfortable car so I'm greener than you," you have the government calculating how many miles you drive and sending you a bill. And knowing where you are, and how fast you're driving and where you stopped for the night and what route you take to work, etc. Everyone with a vehicle will effectively be wearing an ankle bracelet just like those guys on parole.

Along with the red-light cameras, RFID tags for toll roads and GPS-enabled cell phones, every motorist in America could be located on some Internet map. Sure there would be benefits to the public and to government, but at the bottom of all this beneficial technology is the key question: "How can we extract more cash from the public?"

Vehicles do need roads, and somebody has to pay for them. It sounds logical that the more miles you drive, the more you should support the infrastructure. However, a Prius and a motorcycle don't tear up the roads. Heavy trucks do. Escalades with six overweight car pool riders do -- OK, so that's going too far. But penalizing green vehicles while building an infrastructure to track and tax every vehicle in the country is a very bad idea.

Wayne Hanson  |  Senior Executive Editor, Center For Digital Government