While the deadline for the rest of the country stands, for the national capital, which is choking on thick toxic smog, the deadline for introduction of BS-VI - equivalent to Euro-VI grade, has been preponed to April 2018, the Petroleum Ministry said in a statement.
Automobile manufacturers said Euro-VI grade vehicles will not hit the roads before 2020 but the advancement gives them confidence to make investments in manufacturing such vehicles.
A couple of new refineries are already capable of producing Euro-VI grade fuel, which contain 10 parts per million (ppm) of sulphur as against 50 ppm in Euro-IV fuels.
Delhi consumed 906,000 tons of petrol and 1.26 million tonnes of diesel in 2016-17 and meeting that requirement from April next year would not be a problem.
"Taking into account the serious pollution levels in Delhi and adjoining areas, Petroleum Ministry in consultation with public sector oil marketing companies has decided for preponement of BS-VI grade auto fuels in national capital territory of Delhi with effect from April 1, 2018 instead of April 1, 2020," it said.
Fuel retailers have also been asked to examine the possibility of introduction of BS-VI auto fuels in the whole of national capital regions, which also includes adjoining cities of Ghaziabad, Noida, Gurgaon and Faridabad, from April 1, 2019.
In a Twitter post, Oil Minister Dharmendra Pradhan said "the decision to prepone the introduction of BS-VI grade fuel in NCT of Delhi w.e.f. 1st April 2018 in place of 1st April 2020 as a sincere effort to curb the vehicular pollution in Delhi and adjoining areas."
The introduction of Euro-VI grade fuel is expected to help mitigate the problem of air pollution in NCT of Delhi and surrounding areas, the statement said.
Fuel meeting BS-IV or Euro-IV emission norm was introduced across the country from April 1, 2017.
"Migration to BS-IV grade fuels shows India's resolve to cut down emissions," the statement said. "As a next step in this direction, Government in consultation with stakeholders has decided to meet international best practices by leapfrogging directly from BS-IV to BS-VI grade by April 1, 2020, skipping BS-V altogether."
Oil refineries will need to invest Rs 28,000 crore in upgrading petrol and diesel quality to meet cleaner fuel specifications by 2020.
Welcoming the initiative, Abhay Firodia, President, SIAM said the early introduction of BS VI fuel gives confidence to the Auto Industry that BS VI Fuel will be available across the country from 1st April 2020, when the Auto Industry will fully migrate to manufacturing only BS VI compliant vehicles on a pan India basis.
Availability of BS VI fuel in Delhi from April 2018 also gives an opportunity to vehicle manufacturers in this region to test and validate the BS VI vehicles being developed by the auto industry so as to be fully ready for the April 2020 deadline, he said.
Mahindra & Mahindra Managing Director Pawan Goenka said it was unlikely that automobile manufacturers would be able to bring Euro-VI vehicles by next year.
"I don't foresee any mainline player with multiple models being able to launch complete portfolio of BS VI compliant vehicles by April 2018," he said.
According to Indian Oil Corp (IOC), for petrol engines, one of the most critical specification is Research Octane No.
(RON), which has improved from 88 in BS-II to 91, which is at par with regular 91 octane gasoline (petrol) required for Euro VI emission norms.
Sulphur specification for petrol and diesel will be reduced 50 times for a level of 500 ppm for BS-II fuel to 10 ppm in BS-VI.
Previously, the fuels meeting Euro-IV or Bharat Stage (BS)-IV specifications were to be supplied throughout the country by April 2017 and BS-V or Euro-V grade fuel by April 1, 2020.
But now instead of step-wise upgradation from BS-IV to BS-V and then from BS-V to BS-VI, the government plans to switch over directly from BS-IV to BS-VI auto fuels by April 1, 2020.
Oil refineries had previously upgraded technology and invested over Rs 55,000 crore for production and supply of BS -III/IV fuels.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)