From 1 April 2020, all cars, two-wheelers, three-wheelers, buses and trucks sold in India will have to meet the country’s stringent emission standards: Bharat Stage 6 or BS-VI / BS-6. This is equivalent to Euro 6 emission standards that are already in place in many countries since 2015.
India is leap-frogging from BS-IV emission standards directly to BS-VI to become at par with the developed world in emission norms and battle rising pollution levels in many Indian cities.
That doesn’t mean that by April 2020, all other vehicles will have to be off the road. Vehicles that adhere to BS-III / BS-IV emission standards can continue to ply as long as they have a valid registration (of 15 years). Diesel vehicles in the Delhi-NCR region will be allowed to ply for only 10 years, in a bid to reduce the number of diesel vehicles on the road.