In our bi-monthly Seattlemag.com column And Another Thing…, Knute Berger–who writes regularly for Seattle Magazine and Crosscut.com and is a frequent pundit on KUOW–takes an in-depth look at some of the highly topical and sometimes polarizing issues in our city.

So, you thought saving on gas and reducing gas mileage was helping things, but when it comes to the state gas tax, we’re in trouble. Washington’s gas tax isn’t generating enough revenue to pay for our transportation needs, so the Washington State Transportation Commission is looking to the future with a new idea: charge people for the miles they drive, not the gas they burn.

That way the gal driving a Prius or Tesla pays the same as a guy in a Hummer, when it comes to using the roads.

Pay-by-mile is, essentially, a means of tolling all the roads, not just bridges or commuter lanes.

The Transportation Commission wants to test it out with some willing drivers. One means of doing it would be to put a device in each car that reported miles driven to Big Brother—er, the state. The technology to do that exists and could be linked to the vehicle or your smart phone. One concern some people have is whether it would provide users with privacy. The idea is that you would get taxed for use of the state’s roads, but that the state wouldn’t know where you would go. But that data could also well exist.

From a consumer standpoint, it seems fairly straight forward: you drive, and you get a tax bill. But it’s frustrating on several fronts beyond the privacy implications. For example, spending less on gas should be rewarded, right? Gas prices are currently low, and fuel efficiency is high. Shouldn’t we get to enjoy paying less gas tax? For a few minutes anyway?

Another problem is that such taxes are somewhat regressive—a humble Honda is treated the same as a Hummer. An itinerant gardener or junk hauler pays the same as a Porsche driving Microsoftie. Is there a way the tax could be tagged to the value of the vehicle, or the salary of the owner?

But even if there were, doesn’t the new system change our idea of the commonweal? We used to build infrastructure for everyone, whether you used it or not. It was for the common good. Now we’re used to paying user and consumption taxes, but the roads and streets have always been—in Washington anyway—a place where anyone can go. Do we want tolls and mileage fees that limit mobility? How far to we take it? Should be have sidewalk user fees too?

One thing that might make it more palatable: I pay for every mile I drive, the state pays me back for every hour I’m trapped in gridlock. Just a thought.

Pay-per-mile might decrease wasted trips and encourage more use of transit, bikes, and walking, all good for the planet. On the other hand, if it’s successful as a conservation measure, it would fall into the same trap as gasoline: you might be taxing something that overs diminishing returns.

Won’t that lead us right back where we are now?