A diversity of vehicles can be found in India such as BSIII, BSIV and even BSVI with various fuel types Petrol, Diesel, CNG, LPG, and Electric. Hence a colour coded system is useful to identify the different type of vehicles. By the Supreme courts directive of having colour-coded stickers that indicate the fuel type, Ministry of Road Transport and Highways (MoRTH) has issued a notification and advised states to ensure that vehicles conform to the new rules.
The colour-coded Hologram sticker is basically a third number plate affixed to the bottom-left side of the windshield from the inside. It will have an orange colour background for diesel vehicles, light blue background for petrol and CNG vehicles and grey background for all other vehicles. The third registration plate will also bear registration number registering authority, a laser marked PIN and engine and chassis numbers.
The idea behind this is could be to restrict more polluting vehicles to enter a certain area which has already been heavily polluted much like the concept of a Green Zone near the city centre where only fully electric vehicles are allowed to enter. The Honourable Supreme court had instructed the Indian Government to start using colour coded stickers on all vehicles and the process was supposed to be implemented from October 2018 in Delhi-NCR.