Which fraction is used as fuel for heavy vehicles such as trucks and buses?

• A. Diesel — fuel for heavy vehicles such as trucks and buses.
• B. Refinery gas — used in cars.
• C. Petrol — used for light vehicles.
• D. Lubricating oil — domestic heating.

Answer: (A)

Heavy vehicles need a fuel that provides high energy and works well in engines that rely on high compression and strong torque. Diesel is a heavier fraction obtained from crude oil's distillation and burns efficiently in compression-ignition engines, giving the power and fuel economy needed to haul heavy loads like trucks and buses. Petrol is a lighter fraction suited to spark-ignition engines in many cars. Lubricating oil isn’t used as fuel; it’s for reducing friction in engines. Refinery gas is a light fuel mainly used for heating or cooking, not for powering heavy vehicles.