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Difference Between BS4 and BS6 Emissions: BS-IV vs BS-VI

Difference Between BS4 & BS6

The Indian Government constituted specific Bharat Stage Emission Standards (BSES) regulations to control vehicular pollution.  As a result, the Central Government has made it mandatory that all vehicle manufacturers, both two-wheelers and four-wheelers, must manufacture, sell and register only BS6 engines (BSVI) from 1st April 2020.  These set emission standards have been made mandatory to control pollution levels.

Learn the difference between BS4 and BS6 engines, emissions and performances.

Bharat Stage (BS) Standard Emissions Overview

The Bharat Safety Emission Standards instituted by the Government of India are emission standards to control and regulate the output of air pollutants from the vehicles commuting on the road. Moreover, the Ministry of Environment, Forest and Climate Change set these permissible pollution levels and timelines for implementation by vehicle manufacturers.

For CNG usage on BS6 vehicles, manufacturers make certain modifications to maintain the gap between petrol and diesel emissions. So, it is just a matter of time before the manufacturers begin offering CNG adaptable BS6 engines in India. One of the primary differences between BS4 and BS6 is that the latter requires efficient use of technology in the exhaust system of a vehicle as its emission norms are more stringent than the former.

When buying bike insurance or car insurance, you should be fully aware of the emission norms that your vehicle adheres to. This will be useful to avoid any hassle while claiming the amount later.

What is BS6 (BS-VI)?

The automobile industry was mandated to follow certain parameters to control the pollutants output from the vehicles commuting on the road. The BS6 emission standard is considered the 6th iteration of the emission norm, and comparatively, it is a significant leap when considering minimising pollution than the outgoing BS4. This was also because BS5 (BSV) was skipped to introduce better emission rules.

What is BS4 (BS-IV)?

Besides knowing the BS6 emission or BS6 engine, it is crucial to understand the BS4 emission norms, performance, engine, and significance.

The BSES, the governing body for the emissions from all categories of vehicles in the country, introduced the first emission rules and regulations with the name ‘India 2000’ in the year 2000. Moreover, BS2 and BS3 were introduced during 2005 and 2010, while BS4 regulations in 2017 came with more stringent norms and standards.

In case of insurance, if an individual applies for car insurance with a BS6 compliant engine, they can avail quick insurance policy with substantial financial coverage against an affordable premium. Therefore, it is essential to check these factors before availing a motor insurance policy.

Difference Between BS4 and BS6

Both BS4 and BS6 emission standards that set the maximum permissible levels for the pollutants discharged from the exhaust of cars or bikes. While the manufacturers use these alterations to upgrade their vehicles with exclusive features and safety parameters, the significant change comes from more stringent permissible rules.

Below are the highlighted differences in the pollution norms between BSIV and BSVI:

  • BS4 emission rules do not allow vehicles to discharge more than 80mg/km of NO2, while the BS6 emission rules have minimised it to 60mg/km. The Particulate Matter (PM) for petrol vehicles has been fixed to 4.5mg/km in the BS6 emission norm.

  • Under the BS6 regulations, the permissible emission limit has been massively minimised. For example, the norm for NOx from diesel vehicles in BS4 is 250mg/km, it is minimised to 80mg/km in BS6 emission rules.

  • Sulphur and nitrogen oxide play a significant role in petrol and diesel motor vehicles. While the sulphur content in BS4 fuel is 50ppm, it is five times lower in BS6 fuel, i.e. 10ppm.

  • For accurate lubrication, sulphur plays a pivotal role. However, for the BS6 fuel, the sulphur component is lower than the BS4 fuel.

  • With the regulations of BSVI, Selective Catalytic Reduction (SCR) and Diesel Particulate Filter (DPF) were included to analyse the discharge levels of BS6 motor vehicles. However, this was not included in the emission standards set on BS4 standard.

  • Moreover, another addition to the BS6 rules is the Onboard Diagnostic (OD), which is unnecessary in the BS4 norms.


By understanding the BS4 and BS7 difference, it is evident that BS6 includes a wide range of mechanical and technical changes in vehicles that l allows cars or bikes to discharge less smoke, reducing pollution levels.

Since the Indian Government is doing its best for the welfare of the citizens, it is essential as citizens put in their best efforts for the safety of all. For instance, apart from having emission compliant vehicles, every individual owning a car or bike should ensure having an insurance policy that will safeguard them from unfortunate incidents.

They can choose reputed corporate agents like Bajaj Finance Limited, providing different financial coverages against car insurance policies, including third-party damage. Moreover, with a strong network of garages across India, one can avail cashless services everywhere.

Similarly, if an individual owns a bike, they can apply for a comprehensive two wheeler insurance policy to safeguard their finances in case of any mishap. One can apply for the policy online from BFL’s website at their convenience. Besides, one can also avail of add-on coverages like breakdown assistance, pillion rider coverage, zero depreciation, etc.

By understanding the difference between the two emission standards, individuals must choose one that will be effective in the long run.

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