The price of diesel fluctuates differently then the price of gas. I have paid as much as 30 cents a gallon more for diesel over the posted price for a gallon of supreme to 10 cents less then the posted price for a gallon of regular. Even when diesel is more expensive then gas I still like the trade off for the 22+ mpg. Currently I am paying less for diesel then I am for gas in my car. I recommend buying what you like when the opportunity presents itself. Gas or diesel are less important than ownership and use!