noun
low fuel consumption; fuel-efficient
Used for vehicles, appliances, or systems that use little fuel. Often appears in advertising and technical contexts.
この車は低燃費で人気がある。
This car is popular for its low fuel consumption.
低燃費のエアコンを探している。
I'm looking for a fuel-efficient air conditioner.
省エネ is a broader term for energy saving, not limited to fuel.
Compound of 低 (low) and 燃費 (fuel consumption).