The rule change does not mean that every petrol car on Indian roads can now use E100. The government has basically expanded the range of fuels that specially designed vehicles can be certified to use. A conventional petrol car approved for E20 — petrol containing 20% ethanol — will not be filled with E85 or E100.

The amendment also changes certain technical and vehicle-classification provisions, including raising the weight threshold for light petrol and diesel vehicles from 3,000 kg to 3,500 kg.

What exactly are flex fuels?

“Flex fuel” is short for flexible fuel. It refers to vehicles that can run on petrol, ethanol, or different mixtures of the two, depending on what the vehicle has been designed and certified to use.

Petrol is refined from crude oil extracted from the earth. Ethanol is a type of alcohol that can be produced by fermenting sugars or starches from plants. In India, common sources include sugarcane and grains. Ethanol can also be made from agricultural residues and other plant material.…