GREAT.....................
No doubt the State of Oregon will see this and try to ram another tax down our throat. Thanks alot. 
Just to make things worse. The higher fuel prices go, the more we pay in some of the taxes. In some states the taxes are fixed amounts per gallon and others they are a percent of the total amount spent. It is like property tax, if the value of the house goes up why does the government need to raise the rate? We all know the answer.
What is worse is how complex things are when it comes to alternate fuels. For example in the county where I live in South Florida the power company needs to burn so much fuel to meet their contracted agreements with the fuel provider. This means that if you find alternate ways to create fuel for power the power company will not use it because saving fuel could jeopardize their pricing for the fuel they now use. Confusing? You bet!
The article you link to is just a short summary of the actual situation. Most states require drivers of big rigs, buses and even motor homes that travel between states to buy at least some fuel in the state. This is to help offset the cost of road repairs caused by these large vehicles. Generally the law does not apply to cars, vans or pickups.