Via GCC: http://www.greencarcongress.com/2017/08/20170814-icct.html
The International Council on Clean Transportation (ICCT) recently contracted with the International Centre for Automotive Technology (ICAT) of India to conduct laboratory and on-road testing of three in-use passenger vehicles—two diesel and one gasoline—to investigate the real world emission performance of passenger vehicles in Indian roads. The results highlight the disparity between test-cycles and real-world emissions as well as the large disparity between gasoline and diesel vehicles.
For laboratory testing, they measured emissions under the Modified Indian drive cycle (MIDC) (similar to NEDC), and the World harmonized Light Duty test cycle (WLTC); cold and hot start tests were performed for each vehicle and drive cycle.
On-road testing was performed using a portable emissions measurement system (PEMS) under two different trip design conditions: one following the driving conditions as defined under the European Real Driving Emissions (RDE) protocol and another following proper Indian driving conditions. On-road tests were conducted 50 km (31 miles) south west of New Delhi.
The test vehicles were a Hyundai Elite I20 gasoline, a Hyundai Elite I20 diesel and a Mahindra & Mahindra XUV 500 W6, all MY2015 and certified to Bharat IV, with less than 17,000 km (10,563 miles) in the odometer. NOx aftertreatment included three-way catalyst (TWC) for the petrol car, and exhaust gas recirculation (EGR) for both diesel cars. . . .
[GRA note: All three vehicles passed the lab Bharat IV type-approval tests using MIDC cycles. WLTC cycle emissions were greater, but the gas car still passed]
Real driving emissions during PEMS testing showed a substantial increase compared to MIDC emission standard values. NOx emissions for diesel vehicles increased between 4 to 6 times when compared to the corresponding standard. For the gasoline car, CO emissions increased by almost 4 times under RDE conditions. Fuel economy was 20 to 25% lower under RDE for all 3 vehicles when compared to type-approval values.
The difference in emissions performance between the diesel and gasoline cars were striking. Real driving NOx emissions from i20-diesel were 18-20 times more than i20-gasoline; real driving NOx emissions from XUV500 diesel were 25 to 66 times more than i20-gasoline.