An unpublished study by the Automotive Research Association of India (ARAI) has raised concerns over the use of E20 petrol in older vehicles, warning that the higher ethanol blend could gradually damage certain rubber components in fuel systems designed for E10 fuel.
The report says prolonged use of E20 may affect rubber parts such as hoses, seals, gaskets and O-rings in older four-wheelers, potentially increasing maintenance requirements over time. However, it found no evidence of damage to metallic fuel-system components.
The study also examined engine durability in passenger vehicles. While one BS-IV engine completed testing without major issues, a BS-VI turbocharged engine developed problems after around 265 hours of operation. Another manufacturer reported no abnormalities after 400 hours, whereas a separate test recorded an exhaust valve failure after nearly 809 hours. The report noted that standard durability tests usually continue for about 2,000 hours, making it difficult to directly link the failure to E20 fuel alone.
Two-wheelers performed better during the evaluation. Tests conducted by three manufacturers found no significant durability or performance issues, suggesting existing motorcycles and scooters are less likely to face compatibility concerns with E20 petrol.
The report also estimates that vehicles running on E20 could experience a fuel efficiency drop of around 2% to 6% compared with E10, depending on the vehicle and engine type.
The findings have sparked fresh discussion as India accelerates the nationwide rollout of E20 petrol. Owners of older vehicles have expressed concerns over possible repair costs and reduced mileage, while the automobile industry has defended the transition.
Leading manufacturers, including Maruti Suzuki, Hyundai, Toyota Kirloskar Motor, Hero MotoCorp, TVS Motor and Bajaj Auto, have said extensive laboratory tests, field trials and real-world data have not shown widespread damage in vehicles currently on the road. They also maintain that newer E20-compatible models have undergone comprehensive validation before being introduced.
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