Govt allows flex-fuel vehicles that can run on E100, amends motor vehicle rules

The ministry of road transport and highways (MoRTH) has notified amendments to the Central Motor Vehicles Rules, adding E100 as an approved fuel option alongside E85 for flex-fuel vehicles. E100 refers to fuel with 100% ethanol content — or near-100%, since small quantities of water improve combustion.

The notification, issued on October 23 and published in the official gazette on October 26, comes into immediate effect. This follows draft rules published on April 27, after which the ministry reviewed public objections and suggestions before issuing the final notification.

Flex-fuel vehicles are designed to run on any mixture of ethanol and petrol, from pure petrol to E100, with onboard sensors adjusting engine parameters accordingly. Brazil currently operates the world’s most mature flex-fuel programme since 2003, where sugarcane-derived ethanol powers a large share of the vehicle fleet – though users typically have a choice to buy petrol with lower ethanol content.

According to the notification, vehicles designed and certified for high-ethanol blends can use E85 and E100 fuels. Conventional petrol vehicles, including those running on the nationwide E20 blend (20% ethanol, 80% petrol), cannot operate on these higher blends without proper certification.

The regulatory update creates a formal pathway for automakers, as several top car manufacturers prepare to launch E100-compatible flex-fuel vehicles in the Indian market to cut crude oil import dependency.

Transitioning to E100 or high-ethanol blends requires significant vehicle reconfiguration: fuel system components — seals, fuel lines, injectors — must be upgraded to handle ethanol’s corrosive properties, and engine management systems need retuning for ethanol’s different combustion characteristics. The fuel delivers roughly a third less energy per litre than petrol, requiring larger fuel tank capacity or more frequent refuelling.