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5th September 2023 (10 Topics)

Toyota’s flex-fuel prototype


Toyota recently unveiled a prototype of the Innova Hycross with a flex-fuel hybrid powertrain, its first car in India with this option, and one that the Japanese carmaker claims is the world’s first BS6 Stage II-compliant flex-fuel vehicle.

What is flex fuel technology?

  • A flex fuel, or flexible fuel, vehicle has an internal combustion engine (ICE), but unlike a regular petrol or diesel vehicle, this can run on more than one type of fuel, or even a mixture of fuels.
  • The most common versions use a blend of petrol and ethanol or methanol, but these engines are also equipped to run on 100 per cent petrol or ethanol as well.
  • This is made possible by equipping the engine with a fuel mix sensor and an engine control module (ECM) programming that senses and automatically adjusts for any ratio of designated fuels.
  • It was first developed in the early 1990sand used in the mass-produced 1994 Ford Taurus, according to Car Bibles. By 2017, there were approximately 21 million flex-fuel vehicles on the road.

Hycross prototype

  • The Hycross flex-fuel prototype has a 2-litre Atkinson Cycle petrol engine coupled with an electric motor, the same as in the hybrid version of the standard Hycross.
  • The prototype can run on petrol with more than 20% ethanol blending that is currently mandated in India, and that its performance would be at par with the standard Hycross hybrid, even with ethanol-blended petrol.

Key Components of a Flex Fuel Car

  • Battery: The battery provides electricity to start the engine and power vehicle electronics/accessories.
  • Electronic control module (ECM): The ECM controls the fuel mixture, ignition timing, and emissions system; monitors the operation of the vehicle; safeguards the engine from abuse; and detects and troubleshoots problems.
  • Exhaust system: The exhaust system channels the exhaust gases from the engine out through the tailpipe. A three-way catalyst is designed to reduce engine-out emissions within the exhaust system.
  • Fuel filler: A nozzle from a fuel dispenser attaches to the receptacle on the vehicle to fill the tank.
  • Fuel injection system: This system introduces fuel into the engine's combustion chambers for ignition.
  • Fuel line: A metal tube or flexible hose (or a combination of these) transfers fuel from the tank to the engine's fuel injection system.
  • Fuel pump: A pump that transfers fuel from the tank to the engine's fuel injection system via the fuel line.
  • Fuel tank (ethanol/gasoline blend): Stores fuel on board the vehicle to power the engine.
  • Internal combustion engine (spark-ignited): In this configuration, fuel is injected into either the intake manifold or the combustion chamber, where it is combined with air, and the air/fuel mixture is ignited by the spark from a spark plug.
  • Transmission: The transmission transfers mechanical power from the engine and/or electric traction motor to drive the wheels.

 How flex fuel cars work?

  • Flex fuel vehicles have one fuel system, and most components are the same as those found in a conventional petrol-only car.
  • Some special ethanol-compatible components are required to adjust to the different chemical properties and energy content in ethanol or methanol, such as modifications to the fuel pump and fuel injection system.
  • The ECM is also calibrated to accommodate the higher oxygen content of ethanol.


Advantages of Flex-Fuel

Disadvantages of Flex-Fuel

  • Cleaner Fuel
  • Flexible Usage
  • Sustainable Source
  • Provides similar, and sometimes better, performance than pure petrol cars


  • Nationwide Adoption: The greatest barrier to flex-fuel adoption is the infrastructure investment required to make the switch.
  • Increased Engine Wear: While the engines will be designed to adjust to the blend of fuel used, the ethanol component in the flex-fuel will cause greater wear and stress on the engines. This might translate to higher maintenance costs during the time the technology matures and improves reliability.
  • Lower Mileage: While ethanol burns cleaner, it also contains less energy than pure petrol.

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