BS4 vs BS6 Engine Difference: What You Should Know Before Buying a Car

If you are buying a used car in India, you may have heard terms like BS4 and BS6. These refer to the Bharat Stage emission standards followed by vehicles in India.

The main difference between BS4 and BS6 is how much pollution the vehicle is allowed to produce. BS6 is a stricter emission standard and uses more advanced emission-control technology than BS4. India moved to BS6 for new vehicles from 1 April 2020.

Let's understand the difference in simple words.

What Is BS4?

BS4 (Bharat Stage IV) is an older vehicle emission standard introduced before BS6.

BS4 vehicles were designed to control harmful emissions such as:

• Carbon Monoxide (CO)

• Hydrocarbons (HC)

• Nitrogen Oxides (NOx)

• Particulate Matter (PM), especially in diesel engines

BS4 cars are still commonly found in the used-car market because many vehicles manufactured before April 2020 followed this standard.

What Is BS6?

BS6 (Bharat Stage VI) is a much stricter emission standard.

The government introduced BS6 for new vehicles from 1 April 2020. BS6 vehicles use improved engine and emission-control technology to meet tighter pollution limits.

Many BS6 vehicles also use systems such as On-Board Diagnostics (OBD) to monitor emission-related components and identify certain faults.

BS4 vs BS6: Key Differences

BS4 vs BS6: Which Is Better?

If your priority is lower emissions and newer technology, BS6 is generally the better choice.

BS6 vehicles were developed to meet stricter emission requirements and can have more advanced emission-control systems.

However, this does not mean every BS6 car will automatically be better than every BS4 car in terms of overall ownership. The car's condition, service history, mileage and maintenance are also very important when buying a used vehicle.

Is a BS4 Car Still Worth Buying?

Yes, a well-maintained BS4 car can still be considered in the used-car market.

Before buying one, check:

• Service history

• Engine condition

• Pollution certificate

• Registration details

• Insurance

• Accident history

• Overall maintenance

Also check the local rules and restrictions applicable to older vehicles in your city, as these can change over time.

Can a BS4 Car Be Converted to BS6?

BS4 and BS6 are emission standards, not simply different engine parts that can be swapped.

Converting a BS4 vehicle to fully meet BS6 requirements is not a simple engine modification. BS6 compliance involves the vehicle's overall emission-control system and regulatory approval.

So, if you specifically want a BS6 vehicle, it is generally better to buy a factory BS6-compliant vehicle rather than trying to convert a BS4 vehicle.

How to Check If Your Car Is BS4 or BS6?

You can check the vehicle's emission standard through its vehicle documents, including the registration-related information. Parivahan's official documents include Bharat Stage IV/VI as emission-norm categories.

You can also check the vehicle details through the official VAHAN/Parivahan system.

BS4 vs BS6 for Used Car Buyers

If you're choosing between two similar used cars, consider:

Choose BS6 if:

• You want a newer emission standard

• You prefer newer technology

• You plan to keep the car for several years

Consider BS4 if:

• The car is in excellent condition

• It has a good service history

• The price is significantly lower

• BS4 vehicles are permitted for your intended use and location

Conclusion

The biggest difference between BS4 and BS6 engines is emission control. BS6 is a newer and stricter standard designed to reduce vehicle pollution and uses more advanced emission-control technology.

But when buying a used car, don't look at the BS rating alone. Engine condition, service history, mileage, ownership history and vehicle condition are equally important.

If you're looking for a reliable used car, Caryanams can help you find and compare options with confidence.

FAQs

1. What is the main difference between BS4 and BS6?
BS6 has stricter emission requirements and more advanced emission-control technology than BS4.

2. Is BS6 better than BS4?
For emission standards and pollution control, BS6 is the newer and stricter standard.

3. Can I buy a BS4 used car?
Yes, but check its condition and the local rules applicable to BS4 vehicles.

4. When did BS6 start in India?
BS6 emission norms for new vehicles were implemented from 1 April 2020.

5. Should I buy a BS4 or BS6 used car?
If both cars are similar in condition and price, BS6 can be a more future-oriented choice. However, always check the individual car's condition and history.