Thanks to improved gas mileage on modern vehicles and a steady increase in hybrid and electric vehicles, the gas tax just isn't what it used to be. Therefore, government now wants to tax based on the odometer rather than the gas tank. Well, it is government; they'll probably tax both. The plan is to install a GPS in cars and then send out the bill based on how many miles the car went during the billing period. Every road instantly becomes a toll road, even dirt roads.
Interestingly, I am sympathetic to the idea, especially if it was actually used to maintain the roads (unlikely). It charges based on use, which is exactly how it should be done. More miles equal more use and thus a higher tax. I like toll roads, especially if they are privately owned. Private owners have a vested interest in making your time on the road pleasant. You are unlikely to take the toll road again if it is full of potholes. On the other hand, government would far prefer to spend that money buying voters; not a lot of people vote based on the state of government-maintained infrastructure. Also, with the GPS, there would be constant information on road usage so the money could be funneled to high use roads. In fact, it would be possible to have the tax allocated to specific stretches of road; it is always best to limit politicians' discretion in the spending of tax dollars.
Of course, there are drawbacks. If you want less of something, tax it. By taxing miles driven, people will drive fewer miles. Would a truck pay more than a Smart car? It would be logical to charge based on the weight of the vehicle, thus taxing motorcycles less than SUVs. If it didn't differentiate on weight, the return of the gas guzzler would follow. If the gas tax was repealed (unlikely), the price of gas would drop overnight by 40 cents a gallon (varies by state but that's an average). The tax also provides a nice lever to prod the people toward mass transit. The higher the tax goes, the more likely people are to take the bus or hop on a subway.
I do not like the idea of a GPS in the car that the state monitors. We have far too much government monitoring as it is. Better to have the odometer read during yearly inspections and a tax be assessed based on that. The tax could be part of the car registration cost:
"Mr. Smith, you drove 20,000 miles over the past year. Your tax is $300."
Oh, did I mention that Oregon - the start up for this new tax - is charging 1.5 cents a mile? That is the starting point. When the income tax was introduced, the top rate was 7% but look at it now. I foresee a higher tax and calls for bullet trains, a beloved government mass transit boondoggle... er... project. If gas taxes were actually spent on roads and bridges, we wouldn't have a problem but, as I mentioned, potholes rarely appear in political ads. Better to take that money and spend it on a new school or a convention center with a politician's name on it; that will attract some votes. The same will be true for this new tax.