This mostly depends on how one drives his/her car and how the car is maintained.
· Over speeding and applying brakes often reduces the fuel efficiency of the car. One should drive the car smoothly and patiently. When accelerating and decelerating the car smoothly, the fuel efficiency of the car will automatically increase.
· Never drive with your foot on the clutch. This results in wastage of engine power which in turn increases fuel consumption and the clutch wears out before time. The clutch pedal should always be used to shift gears.
· Always switch off the engine when idle or when at a red signal for a long duration. This will save fuel.
· Always shift gears accordingly. When the gear is at a higher ratio and the speed of the car is low or when the gear is at a lower ration and the speed of the car is higher, the car consumes more fuel. Always change gears according to the speed of the car.
· Always maintain a constant speed when driving on open roads.
· Aerodynamics of the car plays a vital role to maintain the fuel efficiency of a car. When at high speed, it is always good to pull up the car windows and put on the AC, as it maintains the stability of the car.
· Always keep the tyres properly inflated.
· Always keep the car properly maintained. One should not ignore the basic things such as engine oil, battery, engine filters etc.
· Never run your car on an oversized tyres or small tyres. Wider tyres increase rolling resistance and rotation mass thus, resulting in low fuel efficiency.
· Never overload your car. This put more pressure on the engine and results in low fuel efficiency.