Changes

==Pollution==

==Pollution==

Under certain conditions, diesel engines produce black smoke, see [[Rolling Coal]].  They also produce larger volumes of nitrogen oxides than gasoline engines.  Modern diesel engines are tuned to minimize smoke production and they can be fitted with urea injection systems to reduce emission of nitrogen oxides.

Under certain conditions, diesel engines produce black smoke, see [[Rolling Coal]].  They also produce larger volumes of nitrogen oxides than gasoline engines.  Modern diesel engines are tuned to minimize smoke production and they can be fitted with urea injection systems to reduce emission of nitrogen oxides.

==References==

==References==

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