The EPCA told a bench of Justices Madan B. Lokur and Deepak Gupta that colour-coded stickers, as used in Paris.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/epca-bats-hydrogen-cng-mixed-fuel-curb-pollution
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/asian-age-new-delhi
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/vehicular-pollution
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/hydrogen-energy
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/environment-pollution-control-authority-epca
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-pollution-control