E20 petrol reduces mileage by 3-5% but does not harm engines, government confirms
The government has informed Parliament that E20 petrol, which contains 20% ethanol, may reduce fuel efficiency by around 3 to 5 per cent in some older vehicles originally designed for E10 fuel. However, it emphasised that there is no evidence linking the higher ethanol blend to widespread engine damage or vehicle breakdowns.
In a written reply in the Rajya Sabha on Tuesday, Minister of State for Petroleum and Natural Gas Suresh Gopi said fuel economy depends on several factors, including driving style, vehicle maintenance, tyre pressure, wheel alignment and the use of air conditioning. The drop in mileage for older vehicles is generally limited to 3 to 5 per cent, he added.
The minister highlighted the benefits of E20 petrol, including higher octane levels, improved resistance to engine knocking, better combustion and smoother acceleration. He noted that E15+ petrol has been used widely across the country for over three and a half years, while E19 and E20 fuel have been in use for more than two and a half years.
According to the government, more than 20 crore two-wheelers and over 3 crore petrol cars, including vehicles manufactured before E20 compatibility standards were introduced, have been running on these fuel blends without any verified evidence of large-scale engine failures.
The government cited service records from vehicle manufacturers. One leading carmaker serviced 2.84 crore vehicles during 2025-26, including nearly 1.5 crore older vehicles not certified for E20 fuel, without reporting damage caused by the higher ethanol blend. Similarly, a leading two-wheeler manufacturer reported that vehicles running on E20 fuel did not experience a higher rate of damage than those using earlier fuel blends.
The Centre said automobile manufacturers continue to honour vehicle warranties when customers use fuel that complies with E20 specifications. Laboratory studies and field trials also found no significant differences in the performance of older vehicles. Tests covering drivability, engine starting, and the compatibility of metal and plastic components did not reveal any major concerns.
The government further clarified that it has no plans to return to E0 or E10 petrol. Maintaining separate nationwide supply chains for E0, E10 and E20 fuel across more than one lakh retail fuel outlets would increase logistics challenges, inventory requirements and handling costs, it added.
