US emissions standards versus EU
Since the topic came up in another thread and I did not get a chance to explain myself before it was closed.
As you can see in the links below, US emissions standards are more lenient towards GHG vehicle emissions that cause atmospheric damage like CO and CO2 which mainly come from gasoline engines, and are more stringent towards vehicle emissions that cause health hazards like NOx and PM which mainly come from diesel engines. This puts gasoline engines in a huge advantage even though these emissions they emit do more harm to the atmosphere. The US test cycles also favor gasoline vehicles over diesels as well.
While these stricter diesel emissions standards are needed in heavily populated areas like southern California, they are not in less populated urban areas since these emissions, like NOx, dissipate into the upper atmosphere (where they become good for the ozone) before they have a chance to stagnate causing any health hazards. NOx is only bad in the lower atmosphere and is the sole reason why we have EGR and SCR/DEF systems on US trucks.
EU emissions on the other hand are more lenient on NOx and PM emitted from diesels and are more strict on CO and CO2 which is mainly emitted by gasoline engines. Not only that, but their test cycles are less stringent for diesels as well. This is the reason why a diesel sold in EU will not pass US Emissions standards and why many EU diesels generally have higher power levels versus the same diesel in the US. The less stringent NOx limit is also why many EU diesels do not have EGR's while US diesels use both EGR and SCR/DEF systems to meet the stricter NOx requirement.
We saw this when the Ecodiesel first came out and was delayed multiple times because it was pending the US emissions certification even though it already passed EU emissions standards.
Comparison of US and EU programs to control lightduty vehicle emissions
Differences in US and EU emissions standard key cause of Dieselgate
Comparing Emission Standards and Laws in the US and EU
As you can see in the links below, US emissions standards are more lenient towards GHG vehicle emissions that cause atmospheric damage like CO and CO2 which mainly come from gasoline engines, and are more stringent towards vehicle emissions that cause health hazards like NOx and PM which mainly come from diesel engines. This puts gasoline engines in a huge advantage even though these emissions they emit do more harm to the atmosphere. The US test cycles also favor gasoline vehicles over diesels as well.
While these stricter diesel emissions standards are needed in heavily populated areas like southern California, they are not in less populated urban areas since these emissions, like NOx, dissipate into the upper atmosphere (where they become good for the ozone) before they have a chance to stagnate causing any health hazards. NOx is only bad in the lower atmosphere and is the sole reason why we have EGR and SCR/DEF systems on US trucks.
EU emissions on the other hand are more lenient on NOx and PM emitted from diesels and are more strict on CO and CO2 which is mainly emitted by gasoline engines. Not only that, but their test cycles are less stringent for diesels as well. This is the reason why a diesel sold in EU will not pass US Emissions standards and why many EU diesels generally have higher power levels versus the same diesel in the US. The less stringent NOx limit is also why many EU diesels do not have EGR's while US diesels use both EGR and SCR/DEF systems to meet the stricter NOx requirement.
We saw this when the Ecodiesel first came out and was delayed multiple times because it was pending the US emissions certification even though it already passed EU emissions standards.
Comparison of US and EU programs to control lightduty vehicle emissions
Differences in US and EU emissions standard key cause of Dieselgate
Comparing Emission Standards and Laws in the US and EU
