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Bharat Stage 6 (BS6) Emission Standards: Everything You Need To Know

Bharat Stage 6 (BS6) Emission Standards: Everything You Need To Know

Snapshot: As the Indian auto industry is working rigorously to make vehicles BS6 compliant, we hereby answer a few questions regarding the BS6 Emission Norms. Read on.

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If you wish to have clean air to breathe, clearing the air on BSVI emission norms is essential. Various factors are responsible for the slowdown in the automobile sector. One of the primary reasons is the uncertainty in the minds of the consumer about BSVI emission norms. We aim to clear the air on BSVI emission norms through this feature.

BSVI Emission Norms – The Deadline

April 01, 2020 will prove to be a red-letter day in India’s automobile history, as India takes the leap from BSIV to BSVI emission norms. It is going to be a creditable achievement because the shift will take place within three and a half years by skipping BSV norms. The credit should go to the auto industry and oil companies who have worked tirelessly to ensure the smooth transition before the April 01, 2020 deadline.

Naturally, automakers have their tasks cut out. They have to phase out specific models or powertrains in the bargain to help them make this transition in time. The cost factor is a significant one because it would ultimately pass on to the consumer. Hence, buyers are in a state of confusion, thereby leading to an unprecedented slump in the sales of automobiles. We shall demystify the questions in the minds of the consumers and clear the air on BSVI emission norms.

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BS-VI Emission Norms

The Principal Culprits – Nature of Pollutants

Some of the notorious pollutants emitted by internal combustion engines are carbon dioxide (CO2), carbon monoxide (CO), oxides of nitrogen (NOx) and hydrocarbons. The direct injection petrol engines also emit carbon soot and particulate matter (PM). 

BSVI compliant engines Can Save The Day

Instead of adopting superficial remedial measures, automakers have to go to the root of the problem and eradicate it. It involves working on the engine as well as the treatment of pollutants after the combustion process. Hence, there is a need to have an enhanced combustion chamber design along with a clean fuel injector system to refine the entire combustion process. As a result, you have finer atomization of the fuel leading to a marked improvement in the quality of emission. Exhaust treatment systems can help in arresting the release of pollutants like NOx and PM.

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Particulate filters are the ideal devices to reduce PM emission caused by direct-injection fuel engines. Selective Catalytic Reduction (SCR) system or a Lean NOx Trap (LNT) can tackle the challenge of nitrogen oxide emissions in diesel engine-driven vehicles.

LNT eliminates NOx by filtering it out, whereas SCR employs a different method to reduce nitrogen oxide emissions. The procedure involves injecting a water-based urea solution named AdBlue into the exhaust flow. It is a complicated process, and thereby expensive. Mercedes and Jeep use this procedure in the diesel vehicles introduced in the Indian auto market. 

How is BSVI different from BSIV?

This table will explain it all.

Comparison between BSIV and BSVI emission standards

Engine Type

Exhaust Gas

BSIV Limits

BSVI Limits

Percentage decrease

Diesel engine

CO mg/km




HC mg/km




NOx mg/km




PM mg/km




Petrol engine

CO mg/km




HC mg/km




NOx mg/km




PM mg/km





The table indicates that nitrogen oxide levels and PM should reduce by 68% and 82% in diesel engine-driven vehicles, whereas hydrocarbons should witness a reduction of 43%. In the case of petrol-driven cars, the difference is not much. However, the BSVI emission norms will impact PM production in the case of gasoline direct injection engines.

Impact of Fuel Efficiency and Performance

Reducing exhaust emissions can affect the performance and fuel efficiency of the vehicles directly. Therefore, automobile manufacturers have a challenge on their hands. It is to ensure a cleaner environment without compromising on the driveability and the mileage aspects. Various factors can affect the efficiency and performance of the vehicles in BSVI-compliant engines.

  • The combustion process is slower in comparison.

  • The exhaust after-treatment procedures can increase the back pressure on the engine.

  • PM filters and LNT require periodical regeneration.

  • Reducing sulphur content in diesel can impact the energy content of the fuel.

It requires automobile manufacturers to adopt innovative measures. Tata Motors has worked on the power and torque levels to improve driveability, whereas Mahindra has overhauled the powertrains to enhance performance levels. Reducing engine friction can also improve fuel efficiency.

The Cost Factor

Post-BSVI-compliance, petrol vehicles will be costlier by Rs 10,000 to Rs 20,000, and the diesel engine-driven cars will become dearer by Rs 80,000 to Rs 1 lakh.

BS-VI Emission Standards: Everything You Need To Know

BSIV Fuel Vs BSVI Fuel

BSVI grade fuels will have sulphur content equal to 10 mg/kg whereas it is 50 mg/kg in BSIV grade fuel. The lesser the sulphur content, the cleaner is the fuel. It affects the emission of nitrogen oxides, carbon monoxide, and hydrocarbons. As on date, BSVI grade fuel is available in Agra and Delhi-NCR. By the time the deadline of April 2020 draws near, BSVI grade fuel will be available in other parts of India, as well.

Important points to note

  • BSVI cars need BSVI grade fuel to function correctly. It is because the higher sulphur content in BSIV grade fuels can impact the catalytic action in the BSVI-compliant engines by poisoning the agents. 

  • Mercedes employs superior catalysts that permit BSVI-compliant diesel engines to work on BSIV grade fuel. However, it is an exception to the norm.

  • BSVI-compliant petrol engines can operate safely with BSIV grade petrol.

  • Engine oils with low content of SAPS (Sulphated Ash, Phosphorus, Sulphur) should be used on BSVI-compliant engines.

  • BSIV-compliant cars should not have any problem running on BSVI grade fuel. On the other hand, it can result in a better quality of emissions. 

  • India will continue with the Modified Indian Driving Cycle (MIDC) for evaluating emissions from passenger vehicles even after the introduction of BSVI emission norms.

BSVI Vs Euro 6 Emission Norms

Though similar in many aspects, Euro 6 compliant vehicles need not necessarily be BSVI-compliant. It is because India uses different fuels as compared to their European counterparts. The performance requirements are also different because of the lower average speed in Indian conditions. 

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Final Words

The automobile industry and oil companies are through with their share of responsibilities. The ball is now in the Indian Government’s court to revamp its vehicle scrappage policy, thereby ensuring that quality vehicles ply on Indian roads. It is vital for the conservation of the environment that the polluting cars go off the streets as soon as possible.   

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