The government said the drop in mileage for some older vehicles is generally limited to around 3 to 5 per cent.

NEW DELHI: E20 petrol may reduce fuel efficiency by around 3 to 5 per cent in some older vehicles originally designed for E10 fuel, but there is no evidence that the higher ethanol blend causes widespread engine damage or vehicle breakdowns, the government informed Parliament on Tuesday.In a written reply in the Rajya Sabha, minister of state for petroleum and natural gas Suresh Gopi said fuel economy is influenced by several factors, including driving style, vehicle maintenance, tyre pressure, wheel alignment and the use of air conditioning.The government said the drop in mileage for some older vehicles is generally limited to around 3 to 5 per cent. It added that E20 petrol offers advantages such as higher octane levels, improved resistance to engine knocking, better combustion and smoother acceleration.According to the government, E15+ petrol has been used widely across the country for more than three and a half years, while E19 and E20 fuel have been in use for over two and a half years.It said 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 linking ethanol blending to large-scale engine failures.The government also cited service records from vehicle manufacturers. It said one leading carmaker serviced 2.84 crore vehicles during 2025-26, including nearly 1.5 crore older vehicles that were 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.It also said laboratory studies and field trials 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. It said 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.