Ethanol is Great for the Planet, but Is It Great for Your Car?

There is a clear preference for green cars, and that’s a good thing. Cleaner fuels, lower emissions, and a reduced dependency on oil imports the ethanol push checks all the right boxes. But while the environment may be celebrating, a lot of cars and bikes aren’t.

But there has been a rise in complaints related to fuel leaks, mileage drops, and difficulty in starting engines. Most of these issues have one thing in common: ethanol-blended fuel.

It’s clear there is something else going on with E10 and E20 fuels, because of which so many vehicles 

The Green Shift That Caught Many Off Guard

Ethanol is alcohol-based and made from crops like sugarcane. When blended with petrol, it burns cleaner. E10 means 10 per cent ethanol in petrol, and E20 means 20 per cent. The government is steadily moving toward higher ethanol blends as part of its sustainability push.

But a lot of older vehicles, even ones made as recently as 2017, were never designed for ethanol. And even some newer E20-compatible ones don’t always hold up well, especially when not maintained properly or when parked in tough weather conditions.

Despite the shift toward ethanol-blended fuels, real-world use cases reveal recurring issues. A 1999 Yamaha RX135 began stalling after being filled with E20 fuel and left in the rain; the tank rusted, seals degraded, and it refused to start until the entire system was cleaned and refuelled with a lower-ethanol blend. A 2017 BS4 Honda Aviator with a basic carburettor setup faced starting trouble, fuel smell, and reduced mileage, all triggered after the switch to ethanol-blended petrol. Even a 2024 Suzuki Avenis, an E20-compliant model, showed cracks in the breather pipe and fuel vapour issues after being parked in the sun, proving that even ethanol-ready vehicles can face limitations under certain conditions.

Why Ethanol Isn’t Always Car-Friendly

It loves moisture. Ethanol absorbs water from the air, which can collect at the bottom of your tank, leading to rust, fuel separation, and engine trouble.

It can corrode parts. Older vehicles often have rubber and metal components that don’t react well to ethanol. Over time, parts swell, harden, crack, and leak.

It has lower energy. Ethanol gives you fewer kilometres per litre. Expect a drop in mileage, especially in vehicles without fuel injection systems.

It makes cold starts harder. Especially during monsoons or in colder areas, starting the engine can take longer and lead to carbon build-up.

In order to protect your vehicle from damage the following can be done. 

• Don’t let ethanol-blended fuel sit idle in your tank for too long.
• Try to keep your tank at least three-quarters full if the vehicle is going to sit unused for a few days.
• Use XP95 or XP100 petrol if available. These typically have less ethanol.
• Treat your tank with rust protectants if you own an older model.
• Replace fuel lines and breather hoses more often, especially in hot, humid climates.
• Park in the shade or use a cover when possible. It keeps ethanol from evaporating too quickly.

There is no denying it, ethanol is the direction the industry is heading. But millions of Indians still rely on vehicles that weren’t designed for it. These aren’t just cars and bikes. They’re family rides, daily workhorses, memories on two wheels.

As more E20 fuel becomes the norm, we’ll need to bridge the gap between policy and real-world practicality. Until then, awareness and maintenance are your best allies.