The image with this blog post is not a chop or edit, it's the real deal. That's right, $4.87 a gallon, taken by Diesel Power publisher Steve VonSeggern in the California desert town of Shoshone. Granted, above the norm by anyone's standars, but for how long? In Lake Forest, a suburb of Los Angeles in south Orange County, diesel fuel was $4.49 per gallon, as of the end of the second week of April, 2008.

It looks like the prediction that diesel fuel in the U.S. will go to over $5 a gallon is no longer that far-fetched. In fact, it may be only months away.

The rapid price hike of diesel is doubly-devastating for the all of us. Not to downplay the significance and and financial impact of the increase in price of unleaded, but its rise has not been as steep as diesel. The increased cost of unleaded also does not have as immediate and dramatic an impact on the economy as diesel does, simply because the vast majority of the goods sold in the United States are transported by diesel-fueled vehicles, whether by tractor-trailer or locomotive. So if you think food prices have gone up recently (along with just about everything else), you're probably right.

The question that remains unanswered is what the high cost of diesel will do to sales of upcoming light-duty diesel trucks and passenger cars. 2010 is and was expected to be the watershed year when a flood of new clean diesel models are going to come into the U.S. market.

As I've alluded to in previous posts, even with the difference in fuel costs, the difference in fuel economy with diesels is usually enough to offset the higher price per gallon. But add to that the several thousand dollar premium for the diesel engine option, in addition to the ever-widening gap in fuel prices between unleaded and diesel, and the savings equation becomes a much shakier proposition.

Add to this that despite the demonstrated superiority of diesels in fuel-efficiency even measured against comparable hybrids, Americans' perceptions of diesel remain, by-and-large, overwhelmingly negative, believeing them to be noisy, polluting, slow, and (incredibly enough) LESS efficient than gasoline engines, according to some studies.

So much like when the Prius first came out several years ago, it seems like it will be up to the "early adopters" to go against all prevailing wisdom, and buy these new light duty diesels, in the hopes that in time, perception of diesels will change from dirty, slow polluters to clean, quick efficient engines of the future. But if that shift never takes place on a large enough scale, the prospects for light-duty diesels may be doomed before the first new clean diesel even shows up in the showroom.