The Full Form of BSIV is Bharat Stage 4.

BS-4 or BS-IV (Bharat Stage 4) Emission norms are a set of norms and rules which set the guidelines for the permissible emission levels. The Emission norms are are classified under category of vehicles i.e. Commercial Vehicle, Passenger Vehicle, Light Duty , Heavy Duty Vehicle etc. & further classified under Diesel & Petrol (Gasoline) engine.

The Government Of India fixed a deadline of April 2017 to implement BS-IV / BS 4 norms by all car and bike manufacturers. While most cars on sale in India are already complying to . BS 4 emission norms, various two wheeler manufacturers have now started coming up with BSIV products.  Supreme Court today direct automobile companies to clear all stocks of BS-III vehicles by the deadline. It further said no company will be allowed to sell a BS-III vehicle post March 31.

“The Centre had spent thousands of crores of rupees to upgrade technology to produce BS-IV fuel and the companies could not be allowed to frustrate the government’s initiative to check increasing pollution levels by selling around 8.2 lakh BS-III vehicles which they are holding in stock,” a bench of Justices Madan B Lokur and Deepak Gupta said.

There are many companies which came up with their BS-4 Complaint engines , with some of their engines modified & some with new engines, but soon all of the vehicle manufacturing companies will manufacture all types of engines compliant with BS-4 emission norms. It may be noted that the amicus curiae assisting the court has asked the bench to completely ban the manufacture and retail of all non-BS4 vehicles.

Society of Indian Automobile Manufacturers (SIAM) has came up with data indicating an inventory of around 8.24 lakh non-BS 4 vehicles piled up with the manufacturers. Out of these, around 96,000 are commercial vehicles, over six lakh are two-wheelers and around 40,000 are three-wheelers.