Mercedes Still lovin' Diesels

The lead time for a car is measured in years and export planning nearly as long. Still, I have no animus for Mercedes as they have a well earned reputation for quality, high-end vehicles.

Bob Wilson

 

as long as it's japan, and not here, i'm fine with it. good luck to them, i think the japanese are smarter than that.
have to disagree with mercedes quality though. depends on how you define it. certainly not reliability.

 

It's been reported that EPA has scrutinized vehicles, especially diesel vehicles, that have been certified in the U.S. much more closely since the VW TDI scandal.


http://www.nytimes.com/2015/11/09/business/energy-environment/epa-expands-on-road-emissions-testing-to-all-diesel-models.html?_r=0

After VW cheated, tests got tougher


So if MB U.S.-spec diesel vehicles "shut off" the SCR emission controls below 10 degrees C (50 degrees F) like apparently Euro-spec MB diesels, then it must have been reported to EPA during the certification process (i.e., not a "cheat device"). Even if that's true for MB U.S.-spec diesel vehicles, NOx would have less impact on air quality under those conditions (ambient temps below 50 degrees F) since ozone formation is a function of solar radiation intensity, and it's most likely to be weaker in those ambient temperatures (except possibly high altitudes).

It's unrealistic to expect vehicles to meet regulatory limits under all possible ambient and driving cycle conditions anyway. Four out of four modern gasoline vehicles produced 20 to 40 times more PM than the regulatory limit in very cold ambient temperatures (0 degrees F) in a recent (2014) peer-reviewed study by Environment Canada. Since something like 98% of personal vehicles in the U.S. are gasoline-powered, it could be reasonably assumed that there would be more vehicle miles traveled by gas cars in those ambient temperatures than diesels in 50 degrees F or below ambient conditions.