BS4 Vs BS6 Cars: All Differences Explained In Simple Language

by Mohammed Burman | 06/05/2020
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The BSVI emission standards came into effect in April 2020. Accordingly, all the car manufacturers are not allowed to manufacture BS4-compliant cars. So, what are the differences between BS4 vs BS6 cars? Read on to discover.

Firstly, before discovering the differences between these two kinds of engines, it is necessary to know what BS4 and BS6 are.

kia seltos front three quarters

Kia Seltos, the highest-selling SUV, was launched in India with BS6 engines much ahead of the deadline


Should I Buy BS4 or BS6 Petrol Car?

What is BSIV?

Bharat Stage Emission Standards (BSES), the governing organization which sets the regulations on the emission for all types of vehicles in India, introduced the first emission standards ‘India 2000’ in 2000. BS2 and BS3 were put forward in 2005 and 2010, respectively. While the first three emission standards came into effect at regular intervals, the BS4 ones were put forward in 2017, after a 7-year gap. Some of the updates of these norms over the previous ones included the tailpipe emissions, ignition control and Electronic Control Unit (ECU).


BSVI Vs BSIV: All Your Questions Answered

What is BSVI?

Skipping the BSV ones, the Indian government jumped to the BSVI emission standards, which are the sixth iteration of this series of emission norms. This is a substantial leap as regards reducing pollution in comparison with the outgoing BSIV ones.

What are the differences between BS4 vs BS6 cars?

The BSIV and BSVI emission standards set the limit for the emission from cars. Accordingly, BSIV and BSVI cars comply with the respective emission limits. The BSVI emission norms are more stringent than its counterpart. Refer to the table below to get an insight into the main differences between these two types of emission norms.

Fuel Type

Pollutant Gases



Petrol-powered cars

Particulate Matter (PM) Limit

<4.5 mg/km


Nitrogen Oxide (NOx) Limit

<60 mg>

<80 mg>

Diesel-powered cars

HC + NOx

170 mg/km

<300 mg>

Particulate Matter (PM) Limit

<4.5 mg/km

<25 mg>

Nitrogen Oxide (NOx) Limit

<80 mg>

<250 mg>

Frequently asked questions on BS4 vs BS6 cars

Can I fill BS4 cars' engine with BS6 fuel?

It is totally possible for you to fill BSVI fuel in BSIV cars or even older versions. The BSVI fuel has additives which help the engine more effectively lubricate.

Can I fill BS6 engines with BS4 fuel?

You can but it may not conform to the BS6 norms.

Can I convert a BSIV car to a BSVI car by myself?

You can but this is very time-and-money-consuming and illegal. 

maruti vitara brezza front three quarters

The Maruti Vitara Brezza is one of the last cars in its segment to have received an upgrade to become BSVI-compliant.

Is there any difference between the prices of BS4 and BS6 fuel?

Before the BS6 emission standards started to be implemented all over India, they had come to effect in Delhi NCR. There are no differences between the prices of the BS4 and BS6 fuel. Nevertheless, there may be some differences once the norms started to take effect all over India. This can be explained by the input expense invested by the Oil Marketing Companies in upgrading the facilities.

What is the fate of BS4 cars after April 1, 2020?

No new BSIV cars can be produced or registered by the RTO after April 2020. Nevertheless, up to date, no deadline has been set for these cars to stop operating on Indian roads. Therefore, until further notice, BS4 cars are still be allowed to run on the roads.

What are the discrepancies between BS4 and BS6 cars' performance?

The BSVI motor is cleaner than its BSIV counterpart. In some cases, upgrades to BSVI lead to a decrease in the overall output figure and the fuel mileage of the car. Car companies are trying their best to achieve a balance among emissions, performance and fuel efficiency.

Are there any differences between BS4 and BS6 cars' fuel efficiency?

There are only marginal differences between BS4 and BS6 cars' fuel economy. For instance, the claimed fuel mileage of the BS6 and BS4 Maruti Dzire is 21.21 kmpl and 22 kmpl, respectively, which records an insignificant decrease. 

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