ARAI Report Says E20 Fuel May Damage Rubber Parts in E10-Compliant Vehicles
By Arjun Nair
Published July 7, 2026

India's countrywide transition to E20 petrol has reignited concerns about the effects of increased ethanol blending on older cars, particularly after a recent report from the Automotive Research Association of India (ARAI) highlighted possible risks to rubber fuel-system parts in vehicles designed for E10.
The ARAI report advocating for the introduction of E20 has not been released to the public, yet it has been an important reference for the government and vehicle manufacturers. It suggested that these rubber parts may need replacement.
What Happens If You Accidentally Fill E20 in an Older Car?
The ARAI findings relate to prolonged use in vehicles designed only for E10, where material wear becomes a long-term concern.
There is a high risk of damaging rubber parts like hoses, O-rings, Gaskets, and seals. Unfortunately, with no option left, everyone who has a car that is not compatible with E20 petrol is also having to refuel with E20.
E20's Lower Energy Content Explained
One reason some older vehicles may experience a slight drop in fuel efficiency on E20 is that ethanol contains around 30-35% less energy per litre than petrol.
Although modern engine control units (ECUs) can compensate by adjusting fuel injection and ignition timing, vehicles not calibrated for E20 may consume marginally more fuel under similar driving conditions.
Also Read - Govt Plans Up To 15% Isobutanol Blending in Diesel to Cut Oil Imports
Mileage Is Expected To Drop Slightly
Another finding from the study was a 2-6 percent increase in fuel consumption when vehicles ran on E20 instead of E10 petrol. This is primarily because ethanol contains less energy per litre than conventional petrol.
The exact reduction in fuel economy depends on the vehicle, engine calibration and driving conditions, meaning some owners may notice only a marginal difference while others could experience a more noticeable drop.
Which Cars In India Are Already E20-Ready?
Most cars manufactured since April 2023, and all petrol cars sold today are E20 compatible. Automakers have upgraded fuel-system components, engine calibration, and material compatibility to support the higher ethanol content.
Also Read - A List Of All The E20 Compatible Cars On Sale
Why India Is Pushing E20 Fuel
The Indian Government’s goal is to reduce crude oil imports, support sugarcane farmers, and lower tailpipe emissions. India has achieved the 20% blending target well ahead of its previously planned 2030 timeline.
Source: Times Of India
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