I agree with Doug on this one.
Personally, I think all things should be taxed according to any problems they create in other areas.
For example, anything that pollutes, should be taxed as much as it is needed in order to clean up the pollution.
Oil would most likely have a particularly high tax in this area due to both environmental problems it creates as well as protecting the movement of oil which would most likely be done regardless of foreign policy. Also oil money goes to people who are cause huge amounts of human suffering something that should be unacceptable to the US. And the US is basically funding both sides of its "war on terror".
I think it would perhaps be fine to create a system also where by people who rely on certain cars for work, that they would not have to pay a tax for gasoline. But the average person who insists on driving gas guzzling cars would need to pay, especially if they have no good reason for it.
I think a system like this would reward companies who are responsible with the environment and/or don't cause the government to have to spend money to clean up after them or protect their interest with government money.
This is better for the free market. Why? Because it helps allows competition, whereby the price that people are paying, for whatever product, are the true price that it costs. This would cause competition with true prices and would cause companies to look for ways to make/create their products so they don't have to be taxed because they don't have "issues and problems" attached to them. If people were paying the true price for gasoline, I think they wouldn't have bothered doing it for so long, because competition would have been allowed, which I think would have made it an unacceptable option to people a long time ago. Therefore this tax method, would deter companies from providing products that are harmful.
In my opinion, the free market needs government regulation. The government needs to protect competition. Competition does not happen naturally because there are greedy people who just want control and power.
The problem here though, is that there are powerful people who would not want the system to change because they are happy to claim that the system is a true free market so that it sounds like they are justified in their corruption and disregard for what is good for life in general. Of course they are using politics and all. It may not always even be that contrived, it may just be more unconscious sometimes or people look for ways to justify it publicly, or maybe even to themselves.