If it weren't so serious, it might pass as a Ron White joke: Diesel fuel is hovering around $4.75 a gallon, there's an energy crisis in America, and brand new diesel trucks have gone from getting 18-20 miles per gallon to barely getting 10 mpg. It just doesn't make sense.
Why has the fuel economy on the 2007-and-newer diesel pickups been driven down in spite of high fuel costs?
You have to check your history to understand that one.
Congress and the EPA (a government agency-the same government that is crying about getting away from oil dependency) apparently could care less about fuel consumption when it comes to diesel trucks.
Why? The focus is on emissions. At least it was on emissions five years ago when Congress established regulations for future diesel engines-five years before fuel tripled in price. Everything we're seeing implemented now is based on research that dates to years prior to 2003. Remember what fuel cost in 2000? Nothing close to what it does now.
The research behind the Clean Diesel Act of 2003 was all about emissions. Soot reduction. Carbon reduction. Noise reduction. It just so happened that the manner in which those three areas were addressed (particulate traps, EGRs, air intake baffles) resulted in another reduction: fuel economy. But back then, fuel economy wasn't on the front page of these reports because energy wasn't a national issue like it is now. Nobody really cared because fuel was cheap.
Emissions were the primary problem and the EPA wanted change. But when you follow a government timeline, you get change about four years after policy is introduced. The Clean Diesel Act set forth the requirements for the 2007-10 standards and the 2011 standards. That included a sulfur content no higher than 10 parts per million (we're at 15 ppm now thanks to the 2007 National Clean Diesel Campaign), a maximum aromatic content of 15 volume percent to "help reduce air pollution, including particulate matter emissions" (Clean Diesel Act, 2003) and an increase in the maximum cetane number, because "Cetane is helpful in reducing air pollution."
Again, to understand why we have clean-burning diesels that drink enough fuel to make a Hummer look economical, we have to keep in mind that this act was written in 2003. All of these lines in the act were written several months before the national average price for a gallon of diesel fuel spiked to $1.45.
Here's one of the few mentions of fuel economy in the entire act:
CLEAN DIESEL MOTOR VEHICLE- The term `clean diesel motor vehicle' means a motor vehicle with an internal combustion engine that . achieves at least 125 percent of the 2002 model year city fuel economy.
Back in 2000, I looked at buying an `01 Dodge Cummins based on its fuel economy. That model year was getting around 18 mpg city and more than 20 mpg on the highway. In the last few months of this year we've been doing some testing on a 2008 Dodge with the 6.7L "clean diesel" engine. It's lucky if it gets 13 mpg. Does that sound like a 25 percent increase in fuel economy to you? Only in Washington (where the formula in the equation is a constant variable).
You're paying through the nose for these "clean diesel motor vehicles" because the technology to develop them is expensive and you're paying through the nose to keep fuel in them because the fuel economy associated with the clean diesels is in the single-digit to low-10s range. All because five years ago we jumped at the emissions problem without analyzing its effects.
It will probably take Congress another year or two to address the issue of fuel consumption and another five years before anything is implemented to improve fuel economy in diesel pickups.
Here's my take. Fixing the emissions problem by stuffing a ceramic filter in the exhaust pipe (which has to be burned out every few hundred miles by-you guessed it-more fuel) is not the best way to solve the problem. It's like addressing obesity by teaching anorexia. Instead, get rid of all of the emissions hardware that hampers fuel economy (particulate filter, EGR, intake restrictions, etc) and control it through tuning the PCM. Keep the ultra low sulfur diesel fuel and let the engineers do their jobs. There are 600-horsepower custom-tuned trucks on the street that don't blow more than a whiff of smoke.
The bottom line is this: Diesel engine fuel economy is a big issue. And if you wouldn't mind paying five bucks a gallon for another five years, the EPA will get right on it.