This is what really caught my attention:
"Further down the line, diesel could lose some of its allure if the price jumps. Diesel and gasoline prices have been neck and neck in recent years, normally staying within about 20 cents of each other. However, "Diesel use has been growing for several years, and there's no guarantee it couldn't become more expensive than gasoline," says Jeff Hazle, technical director of the National Petrochemical & Refiners Association. Federal renewable-fuel policy is one factor is one factor that seems destined to push diesel prices higher. If so, it will be an unintended consequence of legislation that aims to raise production of ethanol from 4.7 billion gallons in 2007 to 7.5 billion in 2012. That's because the machinery required to grow and harvest the corn that's made into ethanol runs on ... you guessed it, diesel. "I wouldn't go so far as to predict shortages," Hazle says. "But I can't say it's going to be a cheap fuel."

“U.S. overall petroleum demand, including demand for gasoline, has flattened,” he said. “However, in the U.S., demand for diesel has remained strong.” He added: “This follows a long-term trend here and around the world. Over the past five years, U.S. demand for highway diesel has been rising at triple the rate of gasoline.”