The price of gas has actually gone up very little, if at all, over the last 40 years. If we were paying for our gas with gold coins, we wouldn't have seen any change in the prices we pay at the pump! Since the United States dollar is no longer backed by gold, the Federal Reserve has been able to drastically and permanently reduce its value by printing more dollars.
This is a hidden tax on the American people. Our federal government spends more money than it takes in, and makes up the difference by printing new money. This causes inflation and devalues the currency. Wealth is transferred from the American people (whose savings lose their buying power) to the federal government.