First on-road testing for emissions in India proves diesel SUVs and cars emit far more toxic gases than petrol cars

August 12, 2017

One diesel SUV emits as much toxic nitrogen oxide as 25-65 small petrol cars CSE draws attention to the study. Asks – Is India falling in the grip of Europe-style ‘dieselgate’? 

  • Alarmingly high emissions from BS-IV diesel cars and SUVs on road, confirms new study by India’s vehicle testing agency, International Centre for Automotive Technology (ICAT), and US-based International Council on Clean Transportation (ICCT)
  • Adding one diesel SUV to the city fleet in Delhi-NCR is equal to adding 25 to 65 small petrol cars in terms of nitrogen oxide, a very harmful gas that also forms deadly ozone
  • BS-IV diesel cars have at least 1,000 times the number of smaller ultrafine particles than a well designed BS-VI vehicle
  • Automobile industry must agree to implement monitoring of actual emissions from vehicles while being driven on roads. Merely a laboratory test will not help check poor performance of emissions control systems on road or emissions cheating  
  • While Supreme Court has ordered tightening of emissions inspection of on-road vehicles, the Pollution Under Control certification system cannot measure gaseous and particulate emissions from diesel cars on road

New Delhi, August 12, 2017: SUVs and diesel cars emit far more toxic gases than petrol cars – and this has now been conclusively proven by the first ever testing of actual emissions from diesel and petrol cars while being driven on roads. Centre for Science and Environment (CSE) has drawn attention to tests carried out in Delhi-NCR which show alarmingly high emissions from diesel cars and SUVs.

The results show that adding one diesel SUV to the city fleet is equal to adding 25 to 65 small petrol cars in terms of nitrogen oxide emissions. Bharat Stage IV (BS-IV) diesel cars emit at least 1,000 times more ultrafine particles than a BS-VI vehicle. Nitrogen oxide is a very harmful gas that also forms deadly ozone.

These shocking findings are from the study -- Laboratory and On-Road Emission Testing of In-use Passenger Vehicles in India -- done by the International Centre for Automotive Technology (ICAT), the Indian vehicle testing agency, and the International Council on Clean Transportation (ICCT), a body which was responsible for exposing the Volkswagen scandal in the US. This joint study has tested a BS-IV compliant 2015 model of petrol car (Hyundai i20), diesel car (Hyundai i20 diesel), and a diesel SUV (Mahindra XUV500 W8). These cars were tested first in the laboratory and then with portable emission monitoring equipment while being driven on road.

“This study has confirmed what we already know from ‘dieselgate’ in Europe. Diesel cars and particularly large diesel SUVs are much more polluting on road than petrol cars. With BSVI controlling on-road emissions from diesel vehicles will be more complex and expensive than petrol vehicles. As seen in Europe, it is vulnerable to poor performance on road and to emissions cheating. India must adopt tighter test procedures for vehicle certification as well as implement direct monitoring of actual emissions while vehicle are being driven on road. Europe has already implemented this system,” says Anumita Roychowdhury, executive director, research and advocacy, CSE and head of CSE’s Right To Clean Air Campaign. 

CSE researchers say that this is particularly important in India as the country’s existing Pollution Under Control (PUC) certification system cannot measure gaseous and particulate emissions from diesel vehicles on road. It only monitors the thickness of the black smoke, which modern diesel cars no longer spew out visibly in any case.

Highlights of the study – shocking findings

  • Lab tests show emissions from on-road diesel cars far exceed BS-IV standards: Lab tests of petrol and diesel cars and SUVs – done in the way it is done for vehicle certification -- shows nitrogen oxide (NOx) emissions from a petrol car are well below the emissions standard of BS-IV; but the emissions are much higher from a diesel car. More worrying is the very high number of extremely tiny particles bordering on the ultrafine range from diesel cars and SUVs. BS-IV diesel cars have at least 1,000 times the number of smaller ultrafine particles that would be present in a well designed BS-VI vehicle.
  • Actual emissions from diesel cars and SUVs on road alarming: The same cars were also tested on the road with portable emission monitors to check actual or real-world gaseous emissions while vehicles are being driven on road. Real world NOx emissions from a small Hyundai i20 diesel car are three-six times the standard, but a whooping 9-12 times the Hyundai i20 petrol NOx levels. As expected, NOx emissions from a petrol car are much lower -- about 0.5-0.7 times the BS-IV standard.
  • SUVs are the worst emitters: Real-world NOx emissions from diesel SUV are 4-6 times higher than its already weak NOx standard which, in turn, is 5 times higher than the petrol NOx standard. Thus, NOx emissions from Mahindra’s XUV diesel SUV are 25 to 65 times higher than that from an i20 petrol. This virtually means that in terms of NOx emissions, adding one XUV diesel SUV to the city’s car fleet is equal to adding 25 to 65 small petrol cars.
  • On-board diagnostic system fails to diagnose emissions anomalies: The on-board diagnostic system (OBD) — the self policing system in cars — is not designed for detecting whole range of emissions anomalies. This study has exposed that the OBD in BS-IV diesel cars is unable to detect problems with several aspects of emissions control system. For instance, in BS-IV vehicles, in-cylinder NOx emissions are controlled by using cooled exhaust gas recirculation (EGR) system. The test has found a mechanical failure (punctured rubber hose) in the EGR in diesel cars, leading to three times more emissions than the fixed limit. But the OBD systems in the car could not detect this.

It is worrying that in India, emissions standards for NOx are more lax for diesel cars and SUVs than for petrol cars, especially under the BS-III and B-SIV regulations. This leads to significantly high NOx emissions. The BS-IV vehicles also have weak emissions control systems. There are fears that vehicles are being tuned for lower particulate matter emissions from the engine but higher NOx emissions while boosting fuel efficiency. This tradeoff is leading to higher NOx emissions.

Automobile industry must accept real world emissions monitoring

The BS-VI regulations have provided for real-world emissions testing with portable emission systems while vehicles are driven on road. But Indian automobile industry wants to substitute real-world emission testing for in-use compliance on road with a lab test. But this is not acceptable as global experience and particularly, the Volkswagen scandal has shown, laboratory testing can be easily compromised. Portable monitoring of real-world emissions are necessary to ensure robust emissions control systems that perform well on roads, prevent industry cheating and stop use of defeat devices. 

The European Union has already implemented real driving emissions testing using portable monitors and has put in force a regulation. All manufacturers, offering vehicles to the European market, have to meet these requirements.

Learn from Europe

India must learn from the ‘dieselgate’ unfolding in Europe. This has exposed how manufacturers are designing emissions control systems for passing the certification test in lab and then operate differently on road to reduce the severity of the NOx control system. This is leading to unacceptable levels of NOx emissions on road. 

This has already led to a serious backlash against diesel cars in Europe. European and other cities across the world are gearing up to ban, or restrict, or tax diesel cars. Paris has banned pre-1997 diesel vehicles and is now extending the ban to pre-2001 diesel vehicles this year. London is creating an ultralow-emission zone with high road tolls. Oslo enforced diesel ban and fined violators during winter. Stuttgart will ban all except most modern diesels. Munich is framing a plan in response to a court ruling. Mexico City, Athens and Madrid have pledged to ban all diesel vehicles from their cities by 2025. Seoul plans to ban diesel cars made before 2006 from driving in the city’s central districts. Less than 5 per cent of  US cars are now diesel-run, compared to half in Europe.

Act now

These shocking results have serious implications for public health. An IIT Kanpur study has shown that diesel cars are 25 per cent of total car fleet in Delhi, but contribute 78 per cent of the PM2.5 from vehicles. Based on this, the ICCT has separately estimated that particulates from diesel cars represent four times greater cancer risk in Delhi, compared to petrol cars. In fact, more than 280,000 avoidable cancers may be caused in Delhi-NCR over lifetime exposure. Also vehicles are second highest emitter of NOx in Delhi.

  • Implement testing of real world driving emissions with portable emission monitors for in-use compliance with emissions regulations to make advanced technologies of BS-VI vehicles work on road. PUC can test only smoke level in diesel vehicles and not toxic gases and particulate matter.  
  • India must control diesel car growth with pricing and taxation policy to reduce the toxic risk. The SUV segment is the fastest growing and the most polluting segment in passenger vehicle category currently in India. Link to the main ICAT-ICCT

  • Report:

For interviews and other information, contact Vrinda Nagar of The CSE Media Resource Centre, / 9654106253