[bwilson4web]

About a year after I bought my 2003 Prius, the EPA changed the test protocol:

• City / Hwy / Combined
• 52 / 45 / 48 - original
• 42 / 41 / 41 - revised
• 44.6 - user reports, 22 samples (I'm doing a little better)

So I was amused to read:

. . .
Kevin McMahon, a partner at the Martec Group, a consulting firm, says the way the EPA calculates fuel economy and carbon dioxide standards gives gasoline-electric hybrids an unfair advantage over diesels.

In 2006, the EPA revised the way it determines real-world, "window sticker" fuel economy to reflect U.S. driving patterns. The EPA's new sticker rule making assumes Americans drive 43 percent of their miles in city conditions and 57 percent on the highway.

But under fleet average standards for corporate average fuel economy and CO2, vehicles are certified using 35-year-old test weighting of 55 percent city and 45 percent highway driving.

"Diesel vehicles that perform very well at high-load and high-speed driving--where most of America's fuel is used in the real world--are penalized," says McMahon. "Meanwhile, vehicles that perform very well in stop-and-go driving, like hybrids, are over rewarded."
. . .

Source: http://www.autoweek.com/article/2009...NEWS/906299987

The article is more about diesel projects that have stopped. Apparently only the European car makers continue to advocate for diesels. But the article also provides a number of 'bits' that taken out of context, might also be a list of diesel problems. There is no need to criticize the elements of a technology if it simply fails to deliver on the streets and highways.

Bob Wilson