Team AckoAug 13, 2023
The main difference between BS4 and BS6 is the type of fuel used by them. BS6 engines use fuel that contains less sulphur. Hence, BSVI engines produce less harmful emissions and pollutants. Whereas BS4 engines use fuel with real sulphur, hence, more harmful emissions and pollutants are emitted.
To regulate the pollution emitted by cars and two-wheelers, the government of India has put forth regulations known as Bharat Stage Emission Standards (BSES).
The Central government has mandated that all vehicle manufacturers, both two-wheelers and four-wheelers, should manufacture, sell and register only BS6 (BSVI) vehicles from 1 April 2020.
In this article, you will learn about BS4 vs BS6 engine, major differences and performance of the new BS6 engine.
Before we understand about BS6 emission or BS6 compliant engine, let’s understand the current BS4 (BSIV) emission norms, engine, performance, and its significance.
The BSES, which is the governing organization for emissions from all types of vehicles in the country, introduced the first emission norms with the name ‘India 2000’ in the year 2000. BS2 and BS3 were introduced in 2005 and 2010, while BS4 norms came into effect in 2017 with stricter emission standards or norms.
Among the regulations set by the governing body, emission-related changes included tailpipe emissions, Electronic Control Unit (ECU), ignition control, etc. The most visible change was the AHO (Automatic Headlamp On), this is one of the norms under the BS4 which catered to the safety aspect of the new emission standards.
The governing body, Bharat Stage Emission Standards (BSES), regulates the output of pollutants from vehicles plying in the country. The Central Pollution Control Board which falls under the Ministry of Environment, Forest and Climate Change sets the standards to regulate emissions from vehicles in India.
The first emission standard or norm, introduced in the year 2000, was known as ‘India 2000’ and later, BS2 and BS3 were introduced in 2005 and 2010, respectively. While the first three emission norms were introduced at regular intervals, BS4 was introduced in 2017, after a gap of seven years.
The BS6 emission standard is the sixth iteration of the emission norm and comparatively, it’s a substantial leap in terms of reducing pollution compared to the outgoing BS4. This is also because the BS5 (BSV) has been skipped in an effort to move to better emission norms.
The below table offers an insight into the change in the permissible emission levels of BS6 vehicles compared to BS4 vehicles:
Petrol Passenger Vehicle:
Nitrogen Oxide (NOx) Limit
Particulate Matter (PM) Limit
Diesel Passenger Vehicle:
Nitrogen Oxide (NOx) Limit
Particulate Matter (PM) Limit
HC + NOx
Both BSIV and BSVI are emission norms that set the maximum permissible levels for pollutants emitting from a car or a two-wheeler exhaust. Compared to the BS4, BS6 emission standards are stricter. While manufacturers use this change to update their vehicles with new features and safety standards, the biggest or the significant change comes in the form of stricter permissible emission norms.
For a cleaner environment and to address the growing concerns about global warming, the Indian government has fast-forwarded the BS6 pollution norms to 1 April 2020. Hence, the jump from BS4 to BS6 instead of moving to BS5 and then to BS6. Below are the differences between pollution norms between BSIV and BSVI:
BSVI or BS6 is the sixth emission benchmark or criterion in reducing pollution levels when compared to the BSIV or BS4 emission norms. Both are the maximum emission norms which set the maximum pollution from the exhaust of the motor vehicle.
While the BS4 emission norms allow a motor vehicle to emit not more than 80mg/km of NO2 (nitrogen oxides), the BS6 emission norms have reduced it to 60mg/km. The Particulate Matter (PM) for petrol vehicles has been restricted to 4.5mg/km in the BS6 emission regime.
Under the BS6 norm, the limit of pollution has been drastically reduced. While the norm for NOx from diesel vehicles in BS4 is at 250mg/km, it is reduced to 80mg/km in BS6 emission norms. The HC+NOx has been reduced from 300mg/km in the BS4 to 170mg/km, while the PM level has been decreased from 25mg/km to 4.5mg/km.
The BS6 emission norm is not only for motor vehicles but also for the fuel being dispensed. Sulphur and nitrogen oxide plays an important role in petrol and diesel. Compared to the BS4, the BS6 fuel has less sulphur and NOx. While the content of sulphur in BS4 fuel is 50ppm, it is five times lower in the BS6 fuel, which is at 10ppm. As for the nitrogen oxide, the permitted level has been reduced by 70% and 25% for diesel and petrol engines, respectively.
From 1 April 2020, when the BS6 norm kicks in, BS6 fuel will also be dispensed across the country’s petrol pumps from the same date onwards. You can use BS6 fuel in BS4 vehicles.
For proper lubrication inside the engine, sulphur plays an important role; however, for the BS6 fuel, the sulphur is lower compared to the BS4 fuel. This is addressed with additives which act as lubricating agents.
With the BSVI norms, Selective Catalytic Reduction (SCR) and Diesel Particulate Filter (DPF) were included to assess the emission levels of the BS6 motor vehicle; however, this was not part of the emission norms set on BS4.
Real Driving Emission (RDE) has been introduced in the BS6 norms to make sure the emission from the motor vehicle is measured on a real-time basis. This was not part of the BS4 norms.
Another addition to the BS6 norms is the Onboard Diagnostic (OD) which is not mandated in the BS4 norms.
A BS6 vehicle using BS4 fuel will not adhere to the required emission norms due to higher levels. Hence, a BS6 vehicle has to use only BS6 fuel to achieve the desired emission levels.
These are emission standards set by the governing body Bharat Safety Emission Standard (BSEB) to regulate the output of pollutants from vehicles plying on the road. The Central Pollution Control Board, under the Ministry of Environment and Forest and Climate Change, sets the permissible pollution levels and timeline to implement the same by vehicle manufacturers.
The abbreviation of ‘BS’ is Bharat Stage and is suffixed with the iteration of the particular emission norms. The Indian emissions standards are based on the lines of European norms commonly known as EURO 2, EURO 3, and so on. The first regulations with the moniker India 2000 were introduced in 2000, with the second and third iteration introduced in 2001 and 2005 with the moniker BSII (BS2) and BSIII (BS3), respectively.
The fourth iteration BSIV or BS4 was introduced in 2017 and the delay between the introduction of BS3 and BS4 resulted in fast-tracking the BSVI or BS6 emission instead of BSV or BS5 norms. Each of these emission norms has stricter emission standards compared to its predecessors.
The table below offers an insight into the implementation timelines of the emission norms:
|Year of Introduction
|Bharat Stage II (BS2)
|Bharat Stage III (BS3)
|Bharat Stage IV (BS4)
|Bharat Stage V (BS5)
|To be skipped
|Bharat Stage VI (BS6)
Vehicle manufacturers will have to make minor changes or modifications to their diesel and petrol engines for the usage of CNG on BS6 vehicles. It’s only a matter of time before manufacturers start offering CNG compliant BS6 engines in the country. CNG powered BS6 cars or vehicles could be a stop-gap arrangement before the era of electric and hybrid vehicles are sold in the country.
The Selective Catalytic Reduction (SCR) unit converts nitrogen oxide (NOx) into diatomic nitrogen and water (both are harmless products) with the help of a catalyst. The SCR unit uses AdBlue or diesel exhaust fluid to reduce NOx emissions. This fluid is made up of two parts – urea and deionized water. When exhaust gases come in contact with the AdBlue fluid, urea is converted to ammonia and carbon dioxide and in turn, the ammonia converts NOx into nitrogen and water vapour, thereby reducing pollutants.
The AdBlue will be filled in a 10-litre capacity tank in smaller passenger vehicles. Currently, AdBlue is being sold by distributors at a premium rate; however, with the rapid increase in sales of BS6 diesel engines, the cost of AdBlue is expected to decline.
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The government has mandated that all vehicles manufactured and sold after 1 April 2020 should be BS6 compliant. Car manufacturers have launched BS6 cars in India. Below is the list of BS6 cars in India that are currently on sale in the market:
|Maruti Suzuki Dzire
|Maruti Suzuki Ciaz
|BMW 3 Series
|BMW 5 Series
|Audi A8 L
|Maruti Suzuki Alto 800
|Maruti Suzuki S-Presso
|Maruti Suzuki Celerio
|Maruti Suzuki Swift
|Maruti Suzuki Wagon R
|Maruti Suzuki Baleno
|Hyundai Grand i10 Nios
|Hyundai Grand i10
|Hyundai Elite i20
|Maruti Suzuki Ertiga
|Maruti Suzuki XL6
|Maruti Suzuki Eeco
|Maruti Suzuki Brezza
|Volkswagen Tiguan Allspace
|Mercedes Benz GLE
|Land Rover Defender
|Land Rover Discovery Sport
|Land Rover Range Rover Evoque
|Maruti Suzuki XL6
|Maruti Suzuki S-Presso
Car manufacturers in India are getting their vehicles equipped with BS6 compliant engines and launching them in India. Also, there are new vehicles which will be launched with BS6 engines. Below is the list of upcoming BS6 cars in India:
|New Mahindra Thar
|New Mahindra Scorpio
|Mahindra TUV300 Plus
|All New Honda City
|MG Hector Plus
Here is the list of BS6 bikes in India that are currently available in the market:
|Honda Activa 125
|Honda Activa 6G
|Suzuki Access 125
|Hero Maestro Edge 125
|Hero Destini 125
|TVS Ntorq 125
|Yamaha Fascino 125
|TVS Scooty Pep Plus
|Aprilia Storm 125
|Vespa VXL 125
|Vespa SXL 125
|Vespa SXL 149
|Vespa VXL 149
|Vespa ZX 125
|Vespa Urban Club
|Vespa Elegante 149
|Hero Splendor iSmart 110
|Hero HF Deluxe
|Hero Splendor Plus
|Hero Super Splendor
|Hero Passion Pro I3S
|Honda CB Shine
|Honda SP 125
|Honda Africa Twin
|Yamaha FZ V 3.0
|Yamaha FZ S V 3.0
|Yamaha YZF R15 V3
|Jawa 300 Classic
|Bajaj Platina 110 H-Gear
|Bajaj Pulsar NS160
|Bajaj Avenger Street 160
|Bajaj Avenger Cruise 220
|Bajaj Pulsar 150
|Bajaj Pulsar 180F
|Bajaj Pulsar 220F
|Bajaj Pulsar NS200
|Bajaj Pulsar RS200
|Bajaj Dominar 250
|TVS Star City Plus
|TVS Apache RTR 160
|TVS Apache RTR 160 4V
|TVS Apache RTR 180 ABS
|TVS Apache RTR 200 4V
|TVS Apache RR310
|Suzuki Gixxer FI
|Suzuki Gixxer SF
|Suzuki Intruder 150
|KTM 125 Duke
|KTM 200 Duke
|KTM 250 Duke
|KTM 390 Duke
|KTM 390 Adventure
|Royal Enfield Bullet 350
|Royal Enfield Classic 350
|Royal Enfield Himalayan
|Royal Enfield Interceptor
|Royal Enfield Continental GT
|Harley Davidson Street Rod
|Harley Davidson Iron 883
|Harley Davidson 1200 Custom
|Harley Davidson Fat Boy
|Husqvarna Vitpilen 250
|Husqvarna Svartpilen 250
Apart from upgrading their bikes to BS6 norms, bike manufacturers are launching new products. Below is the list of upcoming BS6 bikes in India:
|Hero Xtreme 160R
|Hero Xtreme 200S
|Hero XPulse 200
|Hero XPulse 200T
|TVS Scooty Zest
|Royal Enfield Meteor
|Kawasaki Versys 650
The pollution emitted from vehicles in India is measured by government agencies. They use the Air Quality Index (AQI) to gauge the level of pollution in a city. The AQI uses the below criteria to measure emission:
Sulfur Dioxide (SO2)
Nitrogen Oxide (NO2)
Carbon Monoxide (CO)
Particulate Matter (PM)
When the pollution levels are higher, it affects the health and some of the effects are:
Respiratory and heart ailments
Throat and lung infections, asthma
The effects of higher pollution levels on the environment are:
Contamination of air, soil and water
Acid rain and smog
Exhaustion of fossil fuel, the source for petrol and diesel.
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All two-wheelers, including motorcycles and scooters that were manufactured from 1 April 2017 featured the Automatic Headlamp On (AHO). As the moniker suggests, all two-wheelers are required to have the headlights on at all times. In compliance with the BS4 norms, all new two-wheelers will not have a light switch for the headlight, since it needs to be always on. However, the pass and the low and high beam light switch were kept untouched.
The reason behind the introduction of AHO was keeping both the rider’s and pedestrian’s safety. The light remains on during the day as well, which makes it visible to passersby.
Here are the frequently asked questions about BS6 cars and bikes in India:
You can fill BSVI fuel in BSIV cars or older models. Sulphur in fuel acts as a lubricant inside the engine and burns efficiently. The BSVI fuel has lesser sulphur; however, it contains additives which helps in the lubrication of the engine.
The emission from the tailpipe of a BS6 vehicle should match the BS6 norms and this is possible only if BS6 fuel is filled in BS6 cars. While a BS6 car can run on BS4 fuel, it may not comply with the BS6 norms.
Prior to the nationwide rollout of BS6 fuel, it has been implemented in Delhi and the NCR and the prices are not different between BS6 and BS4 fuel. However, this may change once it’s implemented across the country due to input costs incurred by the Oil Marketing Companies (OMCs) towards upgrading their facilities.
You can convert your old car to BS6 standards; however, it requires time and money. Also, it’s illegal.
Currently, there are no new emission norms has been set by the governing body. However, there may be a second version of the BS6 which will include Real Driving Emissions (RDE) cycle. As per this law, the Automotive Research Association of India (ARAI) will test new vehicles in real-world conditions to ascertain the level of pollution. Currently, the test is done in a controlled environment.
The Central government has proposed to introduce Corporate Average Fuel Efficiency (CAFE) in sync with the global auto industry. Under these norms, cars are expected to be 30% fuel efficient from 2022 and by the end of 2021, it’s expected to be increased by another 10%. Through CAFE norms, fuel efficiency will be decided on how many litres does a vehicle consume while running 100kms.
The first emission norm was introduced in 2000, while the second and third iteration was introduced in 2005 and 2010. The BS4 was implemented in 2017, the big gap prompted the government to skip BS5 and jump to BS6 in an effort to reduce pollution in the country.
Yes, all vehicles plying on Indian roads require Pollution Under Control (PUC) certificate as per the Motor Vehicle Act.
No new BS4 vehicles will be manufactured or registered by the RTO after 1st April 2020 when the BS6 emission norms are implemented. However, existing BS4 vehicles will be allowed to run on public roads. Currently, there is no deadline set for BS4 vehicles to stop playing on public roads.
The emission limits for both the Euro 6 and BS6 engine are numerically equivalent, although it could be slightly tweaked to Indian standards.
The BSVI engine is relatively cleaner than the BSIV engine leading to lower combustion. Add new components to the exhaust system and it reduces the overall performance of the car to a certain extent, although not that significant. That said, vehicle manufacturers are developing engines which offer a balance between performance, efficiency and emissions.
The difference between BSIV and BSVI cars’ fuel efficiency is minimal. The BS6 Maruti Dzire has an ARAI certified fuel efficiency of 21.21 km/l while the outgoing BS4 Maruti Dzire returned a mileage of 22 km/l. A slight decline in mileage although not significant.
– June 9, 2020
In an effort to differentiate BS6y vehicles from other vehicles, the Central Government has announced that all BS6 vehicles will bear a 1 cm green sticker. This will come into effect from 1 October 2020 and it will include the registration details. This green sticker will be placed at the top of the registration sticker. Earlier, the government issued a notification that all vehicles will be fitted with a high-security registration plate (HSRP) and will be fitted on the inside of the windshield. The HSRP will also include colour coding for the type of fuel being used by the vehicle. This is done in detecting vehicles which are polluting the environment from those vehicles which are polluting. Now, the 1-cm green sticker is mandatory on the third registration sticker.
– May 27, 2020
The Government of India has announced the BS6 norms for quadricycles in the country. Quadricycles are categorised as L7 in India. While the BS6 norms were rolled to other categories of vehicles, the L7 category was left out. The announcement by the Ministry of Road Transport and Highways has given approval for the full-scale manufacturing of quadricycles in the country. With the latest notification, the process of BS6 for all categories of vehicles is completed. The government said the issued norms were at par with the European Union’s WMTC cycle. Quadricycles are 4-wheeled vehicles that are quite small in size with a length of 3,000mm, a width of 1,500mm and a height of 2,500mm and the maximum top speed is restricted to 70kmph.
– May 26, 2020
The Union Transport Minister said that the government is all set to start the vehicle scrappage policy. Recycling clusters will be built near ports. He also said that through this initiative India, in five years, will emerge as the world’s leading automobile manufacturing hub. Under the policy, old cars, buses and trucks will be scrapped. He also added that the depth of the country’s ports will be increased by 18 meters to accommodate recycling clusters. The recycled material will be utilised by automobile manufacturers to reduce the cost of manufacturing new vehicles.
– April 1, 2020
The road transport ministry has directed all states and Union Territories (UT) in the country to stop selling BS IV vehicles in India from 1 April 2020. With the ongoing lockdown, there are several unsold BS4 vehicles; however, the centre has directed all states and UT to comply with the directive of selling only BS6 vehicles from 1 April 2020. The Ministry in its directive has also attached the Supreme court order to sell 10% BS4 vehicles of the total unsold stock, but this does not apply to Delhi and NCR region.
– March 24, 2020
India’s largest oil manufacturing company (OMC)., Indian Oil Corporation (IOC) became the first company to start selling the cleaner BS6 petrol and diesel in the country. From 1 April 2020, all petrol pumps will begin selling the BS6 petrol and diesel in adherence to the BS6 norms which kicks in from 1 April 2020. The company’s chairman said that more than 28,000 IOC petrol bunks have begun selling BS6 fuel in the country ahead of the deadline. BS6 fuels are being introduced in tandem with the deadline to begin selling only BS6 vehicles in the country from the same date. BS6 fuels are much cleaner compared to the BS4 fuel since it contains less sulphur, leading to lower emissions or pollution.
– March 4, 2020
India’s largest oil company Indian Oil Corporation (IOC) announced that it is ready to supply BS6 petrol and diesel from 1 April 2020. The new BS6 fuels will cost marginally higher than the BS4 fuels that are being sold currently. IOC said that the BS6 fuels will have a sulphur content of 10 parts per million (ppm) compared to 50ppm in the BS4 fuels. IOC has spent close to Rs.17,000 crore towards upgrading its refineries to BS6. The Oil Marketing Company (OMC) said that it has switched to BS6 fuel production a fortnight ago and its containers and depots are ready.
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