Originally Posted by JLewisinSyr

Not really, lets use a hypothetical $4.00/gallon for gasoline and $5.00/gallon for diesel and we'll choose an average run of the mill car that has both a Diesel and Gasoline engine.

The VW Jetta is offered in both gasoline and diesle, the automatic SEL gets 23/30 while the TDI gets 30/42. The cost of Diesel in the above equation is a 25% premium, while the MPG on the TDI is 30% better in the city and 40% better on the highway.

Now, you could say that the Diesel costs more, which it does when comparing it against the lowest model. The lowest equipped Jetta is the S with a price tag of $17,735, while the SEL, which is equipped similiar to TDI is $23,455. The TDI on the other hand is $23,990, but to be fair if you want a sunroof, you'd need to add $1,000. So in the end, the price mark-up like to like is just over $1,500.

Now in driving an average of 12,000 miles a year with each vehicles worst gas mileage (city) you'd need almost 522 gallons of gas for the gasoline and just about 400 in diesel. The cost $2,088 for gas and $2,000 for Diesel, a savings of about $88.00. Trend that out over 3 years of ownership you'd see a savings of about $265.

But during those three years, the maintenance on the Diesel will be less and the resale higher, which is important. The 2006 VW TDI will sell for a premium over the gasoline on average of $2,000, offsetting the initial outlay.

In the end, it's more of the big picture then it is just a single point.