BS3, BS4, BS6 Difference: Emission Norms in Delhi, India

Written by [Devansh], [Employee], Progressive Scrappers | Reviewed by Management
| Last updated: October 2026

If you have ever found yourself looking at your RC book and wondering what BS means there, then you’re definitely not alone. Every winter, car owners in Delhi ask themselves the same apprehensive question: Is my car permitted to be on the roads today? Knowing the differences between BS3, BS4, and BS6 will help you answer it the fastest. This guide is here to show you all the ins and outs of the BS norms and how to deal with the ban in Delhi.

Quick answer: BS stands for Bharat Stage, India's emission standard. BS3 is the oldest and most polluting, BS4 sits in the middle, and BS6, mandatory since April 2020, is the cleanest. In Delhi, the older the norm, the tighter the restrictions.

What Are BS3, BS4 and BS6 Emission Norms?

The Bharat Stage norms are emission norms laid down by the Government of India for regulating the emissions of dangerous pollutants like nitrogen oxides, particulate matter, and carbon monoxide. The standards are similar to the Euro Norms followed in Europe but have been adapted as per the Indian scenario of fuels and roads. The stricter norms are enforced at each successive stage, and better fuel is also required at the same time.

One may be curious about the skipping of BS5 by India. It was decided by the Indian government in 2016 to shift from BS4 to BS6 without including BS5. The move from BS4 to BS6 was made in April 2020, which was quite before the scheduled time. This is the reason why the difference between BS4 and BS6 is far greater than between BS3 and BS4.

BS3 vs BS4 vs BS6 Emission Standards: Key Differences

Here is a simple side-by-side look at the BS3 vs BS4 vs BS6 emission standards.

Rollout dates varied by city, so never judge a vehicle by its manufacturing year alone.

BS3 vs BS4

However, the most notable change was that of the quality of the fuel. The amount of sulphur in the fuel went from 350 ppm to 50 ppm.

BS4 vs BS6

This is where the leap came. Sulphur content fell to 10 ppm, particulate filters were added to diesel cars, and tests were conducted in real driving conditions rather than lab cycles only. The commonly mentioned numbers state that BS6 diesel engines release about 80% fewer particulates and 70% fewer nitrogen oxides than BS4 engines.

BS6 Phase 2 (April 2023)

The BS6 standards themselves were enhanced in April 2023 by introducing Phase 2. The enhancements included the introduction of real driving emissions and advanced on-board diagnostics, which continue to monitor the vehicle's emissions during driving. The car you will be purchasing now is most likely a BS6 Phase 2 one.

How to Check If Your Vehicle Is BS3, BS4 or BS6

Start with your RC book, which often mentions the emission norm. If it doesn't, look for the manufacturer's label near the driver's door or check the owner's manual. A dealer or service centre can also confirm it from your chassis number. You can verify registration details on the Parivahan portal too. Still unsure? Send us a photo of your RC, and we will tell you the norm for free.

GRAP Stages: Which Vehicles Get Restricted and When

GRAP, the Graded Response Action Plan, is Delhi-NCR's emergency pollution playbook, managed by the Commission for Air Quality Management (CAQM). Restrictions tighten as the Air Quality Index (AQI) worsens.

These measures are updated by CAQM from time to time; hence, always refer to its latest order. One thing to remember here is that each subsequent stage builds on the previous one, and Stage III is the stage that impacts old private vehicles.

BS3 Vehicle Scrapping Rules in Delhi

The BS3 category gets the most stringent treatment in the city. During “severe” levels of air pollution, GRAP Stage III prohibits BS3 petrol cars in the entire NCR region, and the ban remains in force until the air pollution levels improve. Challans for violations have reportedly included fines of up to Rs 20,000.

There is a second layer. In December 2025, the Supreme Court modified its earlier order so that authorities can still act against end-of-life vehicles below BS4. So the BS3 vehicle scrapping rules in Delhi lead to a practical conclusion: if your BS3 vehicle is old and barely used, scrapping it through a registered facility is usually less stressful than dealing with restrictions every winter.

BS4 Vehicle Scrapping Rules

Owners of BS4 vehicles fall in an intermediate category. While GRAP Stage III prohibits the use of BS4 diesel four-wheelers on roads, the Supreme Court order clearly states that no coercive measures can be adopted against BS4 and newer vehicles based solely on their age exceeding 10 years for diesel and 15 years for petrol.

In short, the BS4 vehicle scrapping rules don't currently force you to scrap by age alone. Court orders can change, though, so confirm the latest position before you decide.

BS6 Vehicle Scrapping Process

GRAP restrictions don’t apply to BS6 vehicles, nor does any sort of age-related restriction, which means that BS6 owners do not need to scrap their vehicles in normal circumstances. This is done generally because of a very serious incident involving the vehicle, flooding or a fire, or simply a changeover to an EV.

The BS6 vehicle scrapping process follows the same legal route as any other vehicle:

1. Check eligibility and vehicle details on the Vahan portal.

2. Take the vehicle to an Authorised Vehicle Scrapping Facility (RVSF) for inspection and document verification.

3. Hand over the vehicle, which is then dismantled and its registration cancelled.

4. Receive your digital Certificate of Deposit (CoD).

Two-Wheelers and Commercial Vehicles: Do the Same Rules Apply?

That’s not quite accurate. The prohibition of BS3 petrol and BS4 diesel under the GRAP Stage III is applicable only to four-wheelers, so two-wheelers are not covered by that prohibition. However, two-wheelers may fall under age-based restrictions and also have to take the same route for RVSF as four-wheelers if the decision to scrap the vehicle is taken.

Commercial vehicles are on another wavelength. Light commercial vehicles run on diesel fuel and registered outside of Delhi cannot be allowed into Delhi under GRAP Stage III. Goods vehicles registered outside of Delhi also have stricter entry criteria. The direction of CAQM gave limited time to BS4 goods vehicles to run up to 31st October 2026, so transporters need to check with CAQM and the Delhi Transport Department on the current scenario.

Vehicle Scrappage Rules in Delhi NCR: What Owners Should Know

Delhi doesn’t do things alone. The GRAP is implemented for Delhi, Gurugram, Faridabad, Ghaziabad, Noida, and Greater Noida simultaneously. But the process of registration and other things related to it come under the jurisdiction of the respective states’ transport departments; thus, there may be slight variations.

Three habits help every owner. Check the current GRAP stage during winter, keep a valid PUC certificate handy, and keep your RC and ID documents ready. Knowing the vehicle scrappage rules in Delhi NCR before a restriction hits saves a lot of last-minute scrambling. For the national framework, the Ministry of Road Transport and Highways publishes the scrappage policy and rules.

What This Means for You

Treat this table as a starting point, not legal advice. Orders change, so verify before acting.

Why Scrap Through a Registered Facility?

Only a registered workshop is eligible for the issuance of a Certificate of Deposit. The said document will be useful in seeking exemption from paying a registration fee for the new vehicle. In the national scrappage scheme, states can provide an exemption in road taxes up to 25 percent for new private vehicles. This will nullify your previous registration.

At Progressive Scrappers, we guide owners through the Vahan paperwork, explain the scrap value before pickup, and handle the Certificate of Deposit. Our authorisation details are listed on our About page. If you need help with an older vehicle, you can read about our BS3, BS4, and BS6 vehicle scrap service in Delhi.

Conclusion

The differences between BS3, BS4, and BS6 boil down to clean fuel, improved engines, and stringent norms at every level. For those residing in Delhi, this factor will determine the permissible number of runs for your car. Be aware of your norms, monitor GRAP changes, and in case of scrapping, select an authorized center.

Sources: CAQM, Ministry of Road Transport and Highways, Parivahan/Vahan portal, Supreme Court order of December 2025.