Addressing business leaders this week, President Donald Trump argued that the economy was “roaring.” He added that gasoline prices, which are at four-year highs, will be “going down very substantially.”

The average cost of a gallon of gasoline is around $4.50. That is a 50% increase from just a year ago. High gasoline prices are a major reason why approval ratings for the president and Republican members of Congress are weak. The United States is a nation of drivers, and demand for gasoline is relatively inflexible. People have to drive to work and to get groceries, regardless of cost.