Actually, whether is costs more to produce diesel or gas, or whether the refinery is getting rich, the gas stations are getting rich, or OPEC (where they build luxery condos out of sand and money) is getting rich is not relavant....
There is only one reason diesel is more expensive than gas. Commercial operators HAVE to have fuel and homes in winter HAVE to have heat. We can be far more flexible in our use of gasoline.
The crude oil we are processing right now cost us around $100 a barrel (you have to order it and pay for it in advance). That means we paid $2.38 for a gallon of it. It costs us about 19 cents per gallon to process it and turn it into a good clean fuel. That is very efficient BTW.