The automotive industry in India is constantly looking to adopt significant transformations to encourage clean emission driving around the country. One such recent adoption of stricter emission rules is the Bharat Stage Emission Standards (BSES) and norms.
Under the BS norms, there are five variants: BS1, BS2, BS3, BS4 and BS6. Each emission standard is a better variation, and thus, the current battle of BS4 vs BS6 is up for debate. The choice depends on the impact of each on the vehicle's performance and environment.
This guide explains BS4 vs BS6 - which is best - in detail to help you make future car or bike purchase decisions based on performance and impact.
What are the Bharat Stage Emission Standards?
Bharat Stage Emission Standards regulate the emissions of pollutants from vehicles. These standards (set by the Central Pollution Control Board) define the maximum permissible emission levels from a two-wheeler or car’s exhaust.
These BS norms become stricter with each new variation, reducing the permitted emission levels of various air pollutants into the environment. The first emission standard was launched in 2000. Consequently, other emission standards were introduced in 2005 (BS2), 2010 (BS3), and 2017 (BS4).
However, after the new BS6 rule launched in April 2020, only vehicles (both two-wheelers and four-wheelers) compliant with BS6 emission norms are permitted to be sold or registered.
Since this mandate, a number of bike and car manufacturers have launched BS6 variants of their most demanded car/bike models. However, most vehicles still use BS4 engines. So, if you are planning to buy a car soon, you must look for BS6 models that follow the emission regulations set by the government.
BS4 vs BS6 Engine Difference: Fuel and Permissible Emission Standards
Fuel Type |
Pollutants |
BS4 |
BS6 |
Diesel | Particulate matter limit | Less than 25 mg | Less than 4.5 mg |
Hydrocarbon + nitrogen oxides | Less than 300 mg | Less than 170 mg |
Nitrogen oxide limits | Less than 250 mg | Less than 80 mg |
Petrol | Particulate matter limit | | Less than 4.5 mg |
Nitrogen oxide limits | Less than 80 mg | Less than 60 mg |
BS4 vs BS6 Engine: Other Differences
Particulars |
BS4 |
BS6 |
Permitted Sulphur Content | 50 ppm | 10 ppm |
Diesel Particulate Filter | N/A | Necessary |
Additive Properties | N/A | Additives mimicking sulphur’s lubricant properties |
Real Driving Emission | N/A | Implemented with BS6 |
Selective Catalytic Reduction | N/A | Necessary |
Onboard Diagnostic | N/A | Available with BS6 |
BS4 vs BS6 Engine Performance and Impact
Particulars |
BS4 |
BS6 |
Compatibility with Fuel | Only with BS4 engines, as BS4 engines with BS6 fuel, increase the emission levels | BS6 engine uses only BS6 fuel |
Impact on Performance | Less efficient combustion with higher emissions, so less beneficial performance | More efficient combustion with lower emissions, so more beneficial performance |
Impact on Environment | Higher emissions, so worse for the environment | Lower emissions, so better for the environment |
Technology for Emission Control | Limited or complete lack of advanced emissions systems for control and optimisation | Availability of advanced emission systems for control and optimisation |
Impact on Environment
If you compare the environmental impact of BS4 vs BS6, the significant reduction in emission levels with the BS6 engine and fuel ensures a reduced impact on the environment. This, in turn, reduces air pollution due to limited air pollutants being emitted, encouraging a greener environment and cleaner air to breathe.
Impact on Fuel Consumption
The most significant change or upgrade that you will find in BS4 and BS6 is the change in fuel. BS6-compliant vehicles will need BS6 fuel to run efficiently. If you use BS4-grade fuel for BS6 diesel engines, it will result in decreased fuel economy, increased emissions and faults in the fuel delivery system.
Impact of New Technologies
When it comes to BS4 vs BS6 engine performance, it is crucial to note the addition of various new technologies and systems with the BS6 engine. This allows better and more accurate monitoring of the vehicle’s emission levels along with optimal usage of fuel for better efficiency.
Impact on Future Usage
Given the impact of using BS6 engines today, especially on the environment and air quality, it is evident that the future usage of BS4 looks less promising than BS6. Moreover, there are higher chances of stricter prohibitions on BS4 engines in the near future due to their higher emission levels and lack of new technologies.
Summary of BS4 vs BS6 Difference Tables
Let's look at the summary table of differences below to understand which of the two is better, keeping in mind the environmentally conscious population today.
The most prominent difference is the fact that BS6 rolls out Selective Catalytic Reduction and Diesel Particulate Filters that were not included in the BS4 emission norm.
BS6 also introduces Real Driving Emission in India, which measures vehicle emissions in real-time conditions.
Onboard Diagnostics will also be made mandatory with the implementation of BS6.
BS6-compliant petrol vehicles will be 25% cleaner than BS4 due to the reduction in nitrogen oxide levels from 80 to 60 mg/km. For diesel engines, BS6 reduces three pollutants, viz. NOx, Particulate Matter, and Hydrocarbons by 82, 68, and 43%, respectively.
BS4 vs BS6: Which is Best?
To understand which one of the two is better, keeping in mind the environmentally conscious population today, let us look at the summary table of differences below.
Factors for Consideration |
BS4 |
BS6 |
Impact on environment | Less clean air | More clean air |
Emission levels | Higher | Lower |
Fuel efficiency | Optimal | Higher |
Future usage | Limited to permissions and restrictions | Higher compliance with the new emission rules |
Access | Not available with new vehicles | Only available with new vehicles |
Costs | Lower | Higher, as new technologies and better vehicle performance and efficiency |
Looking at the table above, it is clear that BS6 engines are more reliable and better for your car due to multiple reasons, especially its compliance with emission regulations. It might be slightly more expensive than BS4, but given the numerous benefits, the additional cost should not be the main point of consideration.
BS6 is expected to reduce emissions with stricter measures, which will help India fight the battle with rampant air pollution more precisely.
Thus, if you need to choose between BS4 vs BS6 for your new purchase, compare these differences and make your decision.
Does a Bike or Car Insurance Protect My Engine?
In addition to understanding the differences between BS4 vs BS6 engine performance, you must also secure your engines with a comprehensive or
own-damage car insurance policy to reduce your financial burden during unforeseen circumstances.
In India, to drive any vehicle on the country’s roads, you must possess a long-term car insurance policy with the necessary third-party coverage to avoid fines and other consequences.
Reliance General Insurance offers a range of
car insurance plans, including both long-term and short-term policies, to allow you to choose the kind of coverage you want for your vehicle.
Moreover, all our plans come with ample customisation flexibility and many beneficial add-ons. One such add-on is the
engine protection cover, which allows you to protect your BS6 or BSOkay 4 engine from unexpected damage and overall financial loss.
Conclusion
Our country's government announced and established the Bharat Stage Emission Standards after a thorough evaluation to monitor and optimise the air pollution caused by various vehicles.
The aim of introducing stricter emission standards is to encourage and promote a cleaner driving and living environment for citizens. When deciding BS4 vs BS6, you must consider the potential future regulations along with the overall impact of both these engines on the environment and vehicle performance to make the right choice.
Choose wisely to contribute to the greener and more sustainable transportation landscape for the future generation.
Frequently Asked Questions
Which of these two BSES norms offer better power output?
When it comes to power output, the difference between BS4 and BS6 is limited, with BS4 offering better results. However, when compared to the other factors, BS6 provides an overall increase in vehicle efficiency and environmental impact. Thus, the factor of power output should not be the key deciding factor.
Is the BS6 engine more expensive when it comes to maintenance and damage repairs?
For maintenance and repair requirements, BS6 might require more significant out-of-pocket expenses than BS4. This is due to the limited availability of tools and technologies with BS4.
However, investing in a comprehensive or own-damage car insurance policy is recommended as an efficient way to reduce your repair and maintenance expenses in unforeseen circumstances.
Do electric vehicles also have the BS4 and BS6 engines for performance?
No, none of the electric vehicles have any of these engines, as these emission norms are only applicable to engines that run on either diesel or petrol. Moreover, as electric vehicles have electric motors driven by batteries, there is no scope for engine combustion and emissions.
