Huffy-Puffy you are correct. Fact are Facts, Salesman are not. Thank-you for your insight. Just one comment for others out there whom may be confused over this thread.
When you are driving look around and what do you see on the road???? Any vehicle carrying any kind of goods, other than passengers i.e. freight, furniture, appliances, beds, food, etc. outside of RV's has a diesel engine. Why do you think that is??? Diesel engines cost more up front to buy yet on the highway you see many vehicles with diesel engines especially trucks, long haul trucks, etc. Why do you think there are more diesel engine carrying heavy loads than gasoline engines? Do you know there are more BTU's in a gallon of diesel than in a gallon of gasoline, that a fact, pure chemistry. Diesel is more environmentally friendly than gasoline. Diesel is less expensive to refined. Why does diesel cost more than gasoline? Years ago diesel was cheaper than the cheapest gas. But now it is more expensive, simple economic - supply and demand, Europe and other countries use more diesel than we do and they pay more for it so who do you think the major oils are selling there diesel too?? Not us.
The decision to buy a gas engine over a diesel engine is not about the cost of the fuel. From a technical viewpoint I would base the decision on the type of vehicle, the weight of the vehicle and what the vehicle will be carrying most of the time. RV owners tend to carry everything including the kitchen sink. If you are buying a Class C or B gas may be a better choice, if you are buying a Class A then diesel is a better choice. Note Diesel engine passenger car are making a comeback in America with more efficiency than gas and better for the environment.
There are pros and cons for both fuel types just know that the EPA is more for diesel than for gasoline, both fuels are made from the same crude oil. Gasoline cost more to refine.