Adjust for inflation, and adjust by removing the taxes. Hidden and visible. How much is the oil company charging?
That gives a better basis for comparison, even allowing for the fact that a higher tax has a tendency to lower the amount that the oil company can expect to make on a gallon.
Make a historical chart that shows the percentage of the price that went to, and goes to taxes. That will be useful.
The data is there but I cannot find it all in one chart. Gasoline is cheap. If you consider the gains in fuel economy and the overall increases in income historically it’s never been cheaper to fuel your car.
There is no other way to explain why trucks and SUVs are pushing little cars out of the market.