Unlike natural gas, there is no glut of oil worldwide, and the $120 international price of oil dictates what you pay for gasoline, not an excess refining capacity in the USA.
Oil is an internationally traded commodity and Americans are lucky to have to import 50% of their crude oil. And the oil that comes from Canada, comes in at significantly lower prices than internationally priced crude. Oilsands oil from Canada sells for $20 less than worldprice.
Countries like Holland have huge refining capacity and they export gasoline worldwide, all at interantional prices. The pump price in Holland is about $9 per gallon.
In short, you CANNOT make cheap gasoline from expensive oil, no matter how much refining capacity you gave!!!