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Generally, every car has a specific speed where fuel efficiency (i.e. miles traveled per gallon) is highest. This is mostly around 40 - 60mph (~65 - 95 km/h). Above and below this speed fuel efficiency decreases. So if you travel the same distance, you will use more fuel and therefore produce more pollution. In this paper the authors use a pretty ...


First, as far as I remember, there is a major factual mistake (possibly a mistranslation) in the article you quote. What happened is that speeds were reduced by 20 km/h in non-urban areas. I do not recall, and cannot find historical records of, speed reductions to 20 km/h, or in urban areas during the 2014 winter pollution peaks. Specifically, the rule was: ...


There is plenty of photographic evidence of sunrises over Beijing. Taken: 3 May, 2014, Taken by Liu Hongan of Asianewsphoto: Taken: 9 September, 2006, Dan Desjardins Published: 8 July, 2013, Burton Girls Taken: June 8, 2004, Knexon Cho


The most popular emission models (Caline in the US, Copert in the EU) provide emission functions for average trip speeds. This should no be confused with changes to immediate speed (for which there are very few models available, e.g. Modelling instantaneous traffic emission and the influence of traffic speed limits). The answer therefore depends on the type ...

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