By James E. Guyette

Diesels future as a global motor fuel is far from sputtering. Petroleum consumption forecasters are predicting that diesel-powered cars and trucks will be the dominant fuel system of choice for years to come.

Not only will diesel surpass gasoline as the No. 1 worldwide transportation fuel by 2020, diesel will also account for 70 percent of the growth in demand for all transportation fuels through 2040, according to a new study from ExxonMobil.

The relative shift away from motor gasoline to diesel is driven by better light duty vehicle fuel economy and the growth in commercial transportation activity, says the international energy providers 51-page analysis, entitled The Outlook For Energy: A View To 2040. Economic growth and the resulting increased movement of goods and people drive demand for diesel fuel, the report continues, citing heightened population levels and improving economies. About 80 percent of the growth in commercial transport demand will come from developing nations.

Currently diesel powers some 60 percent of the vehicles in Europe, where the fuel is less expensive than highly taxed gasoline. In the U.S. diesel typically costs between 25 cents and 40 cents per gallon more than gasoline, but the difference has been trending downward the past couple of years, according to Allen Schaeffer, executive director of the Diesel Technology Forum. When factoring in diesels relatively higher fuel efficiency, he says the cost differential is less significant.

Even with high fuel prices, were seeing more consumers willing to invest in more advanced technology, fuel-efficient vehicles, Schaeffer says.

And while North Americas thirst for gasoline is expected to decline by one-third through 2040, the ExxonMobil report anticipates that diesels domestic demand will rise by more than 65 percent.

Fuel efficiency has always been a major attraction of clean diesel vehicles, says Schaeffer. Because diesels are 20 percent to 40 percent more fuel-efficient than gas cars, drivers save money with diesels even when diesel fuel prices are slightly higher than gas prices. The significant savings diesel owners experience compared to gas car owners highlights another major reason why clean diesel vehicles sales will increase significantly throughout the U.S. in the coming years, he asserts.

About one out of every two U.S. service stations now offer diesel at the pump, up from one in three a few years ago, according to Schaeffer.