Automobile industry with history of more than 100 years is totally influencing all the economic environments and has very important wellbeing role in the World in every country of the world. Korean Automotive industry in production has only about 40 years but ranked remarkably 6th biggist in the world in the year of 2003. Nowadays The auto, industry has changed into buyer's market in competitively global battle fields and also is changing industry paradigm in product, sales, production, colarboration & emerging, etc. BRICs(Especially China)are rapidly emerging as main producers and customers in new big markets. Korea Auto. Industry faces crictical problems such as higher salary, furious labor union's striking lack of raw material, evasion of 3D works with studying engineering by students which are the key pending agenda that should be overcome for prosperous growth and development of achieving US20,000 GNP.

Diesel engines are the major sources of pollutants in the cities and each country is trying to enforce their emission regulations to reduce the diesel emissions. Expecially Commercial diesel engines have large displacement and they are the major sources of diesel emissions in the cities. This paper introduces the major countries' Diesel Engine Regulations and explains the emission reduction technologies that are currently applied and will be applied in the future.