India, Oct. 27 -- The government on Monday amended vehicle emission rules so that cars can be certified to run on E100 as well as E85, high-ethanol fuels that ordinary petrol cars cannot use and that only flex-fuel vehicles (FFVs) can run on.

E stands for ethanol and the number for its proportion. E85 contains up to 85% ethanol by volume, and E100 is a fuel consisting predominantly of ethanol, according to the Ministry of Road Transport and Highways.

Vehicles certified for these fuels, FFVs, must meet the emission and safety requirements for their category, and the fuels are meant only for vehicles designed and certified to use them. Owners of existing vehicles do not have to switch fuel or modify their cars, and they will continue to h...