I agree with your notion that there are problems with introducing a new tax. However, the biggest problem is that it gives the government it is the large likelihood that the tax will lead to a "permanent" increase in taxation. Any incentives that it gives government to increase pollution are counteracted by the incentives that individuals face to reduce pollution. I would expect there is ample empirical evidence to confirm this.

In dealing with gasoline consumption issues there are many effective was to reduce consumption. Government research while important in the initial push for developing technology is of limited value beyond that. Governments are generally not good at developing finished products so while more funding for research into renewable energy may help they can only go so far in the development of alternative energy sources. In the end it is the profitability of these methods that determine their viability. Again a gasoline tax would help to bridge this gap.

It should be noted that it is quite likely that the gasoline consumption is being subsidized with out considering the risk posed by greenhouse gas emissions. When you compare transportation of goods and people by train to transportation by vehicle you notice that the tracks and land are usually owned by the train company while the roads are usually publicly owned. In this sense vehicle transportation is being subsidized when the gasoline tax is too low. There are economists who I have talked to who believe that even in the absence of issues related to greenhouse gases vehicle transportation is being subsidized.