[mpgmike]

As I recall, the Blue Diamond diesel engine was manufactured in Pennsylvania, but not available in the US. All production was for export use. Because the engine was so incredibly efficient, the EPA had to fabricate some new ruling to prohibit its sale. Traditionally emissions are measured in grams per mile. Using this gauge, the BD was the cleanest diesel engine on the planet. However, the new ruling looked at grams of emissions per gallon of fuel consumed!

The US Jetta Diesel would travel 42 miles on a gallon of fuel. To calculate total emissions, multiply grams per mile by 42. Even though the BD was much cleaner, by the time you multiplied the grams per mile by 72 it looked much worse.