Diesel fuel prices used to be less than gasoline prices. But a lot of people are now wondering why diesel fuel costs higher than gasoline. The primary reason is the increasing global demand. The other factors would be environmental restrictions and higher federal taxes. (All of these will be tackled in detail below.)

What people do not realize is that the pattern shifts. During the summer, people tend to use their vehicles for vacations; this in turn increases the cost of gasoline. During the winter, people tend to stay at home and generate a high demand for heating oil; this in turn increases the cost of diesel fuel. The correlation between heating oil and diesel is that they are similar fuel and that the price of the heating oil tends to set a floor for diesel.