Quote:
Originally Posted by dixy2k
...Diesels have always been subjected to more emission standards than gasoline cars.
Remember the brief period when no diesel cars were sold in US back in the 90's?
Mercedes discontinued diesels starting with MY2000 till... (I can't remember exactly) maybe 2004-2005. Couldn't meet pollution requirements.
CARB states are the worst in this regard.
While different brand diesel were sold in the rest of the country, CA and a few other states did not get them.
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Your memory is somewhat correct, however some of these statements are demonstrably false.
In 2004 EPA implemented the Tier II rules that made the diesel emissions limits for NOx, CO and HC to be the *SAME* as for cars. Note that, until that date, diesels were much dirtier than gassers; afraid you are totally wrong on "diesels were more regulated than gassers". The Tier II standards for gassers were implemented earlier by CARB, however since then there are no essential differences between the two (for emissions of NOx and HC, while CO2 is being used by CARB as a mileage standard.)
The absence of diesels from the US market in the 2004-6 period was due to the fact that no-one could meet particulate (soot, which is a form of HC enhanced by sulfur in the combustion cycle) emissions mandated by the Tier II regs with the low-sulfur (200ppm or more) in that interim period (until ultra-low-sulfur became mandated in 2006), and no-one wanted to ship cars to the US without selling them in CA. (They could have met them with a removable DPF, but maintenance was a nightmare.)
Wikipedia has a more extensive description:
http://en.wikipedia.org/wiki/United_...sion_standards
Also, check their article on ultra-low-sulfur.