DIESEL VERSUS GASOLINE: DO THE MATH
by Robert Patton, TDR Editor
Two years ago (late 2006) I did a payback analysis using a miles-per-gallon and price of fuel comparison.
It was late 2006 and the price premium for ULSD had yet to fully be realized. As this is written (late November) the ULSD fuel is priced half again as much as the 87 octane unleaded fuel ($3.14 versus $1.99).
So much for the diesel engine’s miles-per-gallon advantage…
The following shows how the math worked out in the Issue 55 magazine and in today’s world.
The Fall 2006 ExampleMy own experience has been with a 2002 Dodge 1500 with a 360 cubic inch (5.9 liter) gasoline engine and a 2003 Dodge 2500 with a 359 cubic inch (5.9 liter) Cummins diesel engine. Overall numbers in around-town driving equated to 13.5 mpg gasoline, 18.5 diesel.
In our example, let’s figure that I travel 20,000 miles per year.
| 20,000 | ||
| Gasoline usage: | = 1,481 gallons used | |
| 3.5 |
| 20,000 | ||
| Diesel usage: | = 1,081 gallons used | |
| 18.5 |
It used to be that the price of diesel fuel was less than that of regular gasoline. Lately in my area that has not been the case. However, for comparison sake, let’s assume the numbers are equal at $2.50 a gallon. (November ‘08s numbers are in italics.)
| November '06 | November '08 | |
| Gasoline expense: | $2.50 x 1,481 = $3,702 |
$1.99 x 1,481 = $2,947 |
| Diesel expense: | $2.50 x 1,081 = $2,702 |
$3.14 x 1,081 = $3,394 |
| Diesel net yearly fuel savings: |
$1,000 | – $447 |
| Approximate sticker price for the optional diesel engine: |
$5,500 | $7,100 |
| Years (assuming 20K per year) and miles to payback: |
5.5 years or 110,000 miles |
Never |
Conclusion:
11/06 – I look like a smart guy
11/08 – I pay for the privilege of owning a diesel
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