While CNG and diesel vehicle sales continue to dip, transport department data shows the registration of commercial CNG vehicles increased by 54 per cent - from 19,227 in 2011 to 41, 190 in 2015.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/delhi-5-yrs-sale-cng-vehicles-slides-61-cent
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/indian-express-new-delhi
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/delhi
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/cng
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/vehicles
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/diesel
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-pollution
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/vehicular-pollution
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/right-information-rti
[10] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-pollution-control