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Tata Capital > Blog > BS4 vs BS6: Know What is the Difference Between BS4 and BS6 Engine

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BS4 vs BS6: Know What is the Difference Between BS4 and BS6 Engine

BS4 vs BS6: Know What is the Difference Between BS4 and BS6 Engine

To combat the rising air pollution levels in India, the Central Pollution Control Board (CPCB) has established a set of regulations known as the Bharat Stage Emission Standards (BSES). 

In fact, these emission standards have been made compulsory by the Government of India for keeping pollution levels under control. How? These standards, namely BS1, BS2, BS3, BS4 and BS6, directly mandate controlling air pollutants emitted by the internal combustion engine of vehicles.

You can think of the BS4 and BS6 similar to European Emission Standards (Euro 1 to 4) that were unofficially used for Indian vehicles before the BSES series was put in place. All vehicles on Indian roads are compliant with either of the BSES norms. 

As you would have guessed, BS6 is the latest mandate, and all vehicles sold since march 31st 2020, are compliant with this standard. The key reason behind the switch from BS4 to BS6 compliance is the type of fuel BS6 vehicles will use, which will have less sulphur and Nitrogen Oxide or NOx. 

In this article, we will explore BS4 vs BS6 – the latest additions to the list of emission standards. But before that, let’s clear the basics.

What Is Bharat Stage 6?

The Bharat Stage Emission Standards (BSES) has recently brought in Bharat Stage 6 or BS6, the sixth iteration of the vehicular emission norms. With the implementation of BS6, India’s emission norms will become equivalent to those of developed countries.

Additional Read: What Is BS-6 Engine Technology? How does It Work?

What is Bharat Stage 4?

The Central Pollution Control Board (CPCB) introduced the Bharat stage 4, or BS4 emission norms, in 2017. According to the Bharat stage 4 emission criteria, 50 parts per million sulphur content was permitted instead of 10 parts per million mandated now by the BS6 norms.

BS4 Vs BS6: What is the difference between BS6 and BS4

Here are the key differences between BS4 and BS6:

The main difference between BS4 and BS6 is that BS6 emission norms are stricter than the BS4 criteria. BS6 emission norms reduce NOx emissions by 70% for diesel and 25% for petrol engines compared to BS4 norms. Hence, a BS6 engine requires fuel containing five times lower sulphur traces than a BS4 engine.

Additional Read: Impact of BS6 Engine on Different Types of Cars in India

Pollution Emission Norms (BS4 vs BS6)

Here is how BS4 and BS6 population norms differ:

Pollution NormsBS4 NormsBS6 Norms
Nitrogen Oxides (NOx)80mg/km (petrol engines), 250mg/km (diesel cars)60mg/km (petrol engines), 80mg/km (diesel cars)
Sulphur Content in Fuel50 ppm10ppm
Particulate Matter (PM)25mg/km (diesel cars), not specified for petrol4.5mg/km (diesel cars), 4.5mg/km (petrol engines)
Additive PropertiesNoneAdditives imitating lubrication properties of Sulphur
Diesel Particulate Filter (DPF)Not Available Must be present
Real Driving Emission (RDE)Not combined with BS4Implemented alongside BS6 pollution norms
Selective Catalytic Reduction (SCR)Not Available Must be present
Onboard Diagnostic (OD)Not introduced with BS4Introduced with BS6
Fuel CompatibilityBS6 engines require BS6 fuelBS4 engines using BS6 fuel increases emissions

The Best Option for Car Owners

Recently, the Government mandated that no Bharat Stage 4 vehicle will be sold after April 2020. So, if you’re wondering which is better, BS4 or BS6, it’s always a good idea to choose a vehicle that follows the latest norms, and in this case – BS6. But, it may be challenging to afford a swanky new BS6-compliant vehicle without exhausting your savings.

However, considering the big differences between BS4 vs BS6, investing in a new BS4 vehicle might not be a good idea. That’s where an outstanding alternative to a new car is to purchase a second-hand BS6-compliant vehicle with a used car loan.

Looking for a second-hand car loan? Come to Tata Capital for competitive used car loans interest rates. Enjoy flexible tenures and comfortably finance your BS6-compliant car! Through our portal, you can apply for vehicle finance online and expect a speedy processing in exchange for minimal documentation.  

Start today by checking your used car loan eligibility with the help of a used car loan calculator available on our website, and apply today!

FAQs on BS4 and BS6

What is the power difference between BS4 and BS6?

The power difference between BS4 and BS6 depends on the vehicle’s model and engine technology. BS6 engines typically offer better power output and performance because of their improved combustion efficiency and cutting-edge technology. 

Is BS6 more fuel efficient than BS4?

Unfortunately, BS4 engines may not offer better fuel efficiency even if their engines are designed to be more eco-friendly. Fuel efficiency depends on various factors such as vehicle weight, individual driving habits and engine design.

How do BS6 diesel engines reduce pollution?

The BSVI engine uses a Selective Catalytic Reduction (SCR) unit and AdBlue fluid to convert nitrogen oxide (NOx) into harmless nitrogen and water, requiring periodic refills.

Is BS6 mileage better than BS4?

No, BS6 mileage is not better than BS4. However, BS6 engines are designed to be more eco-friendly.

Can I convert my old car to meet BS6 emission norms on my own?

No, you cannot convert your old car to meet BS6 emission norms on your own. It is illegal. 

What is the full form of BS4 & BS6?

BS4 stands for Bharat Stage Emission Standards 4, and BS6 stands for Bharat Stage Emission Standards 6.