And the real driver for the price of gasoline is the price of oil and taxes. Refining costs +distribution/marketing costs + profits is less than the federal tax alone. The price of oil is largely driven by supply, demand, and speculation. If vehicles converted to natural gas, you would see more demand and speculation on natural gas and, thus, higher prices for natural gas. That would suck for people who use natural gas for heating, and for those who buy electricity from those that generate energy from natural gas.