What are aromatics, what's their chemical composition and how are they manufactured?

Why are there xylenes in gasoline ? What about “clean fuels”?

Xylenes are a natural component of crude oil, from which gasoline is produced after refining. Industry is taking significant steps to reduce the level of aromatic compounds by adapting its formulation of gasoline .

Automotive fuel quality plays an important role in determining the nature and quantity of pollutants emitted by motor vehicles. Cleaner fuels can significantly reduce this source of air pollution.

The European Commission has fixed stringent standards like the total aromatics content in the gasoline that was reduced to 35% from January 1st 2005 at latest.  Further reviews have concluded that there was no need to reduce it further.