How your driving habits affect fuel consumption

The price is still fairly high and this has led to the peddling of myths and theories on how to save fuel. [Jonah Onyango, Standard]

Kenyans have for months on end endured pain at the pump with fuel prices hitting an all-time high in September last year. Petrol retailed at Sh134.72, diesel at Sh115.6 and Kerosene at Sh110.82 per litre in Nairobi.

The latest review which has been on for four months in a row now is a slight relief for motorists with a litre of petrol retailing at Sh129.72, diesel at Sh110.60, and Kerosene at Sh103.54.

The price is still fairly high and this has led to the peddling of myths and theories on how to save fuel.

Laban Mwembi Nyaanga, the Technical Training Manager at Automobile Association of Kenya (AA Kenya) busts the myths and offers some fuel management tips.

Laban Mwembi Nyaanga, Technical Training Manager at AA Kenya.

Is it true that you use more fuel in traffic?

Yes. In a traffic snarl-up, the driver will be in low gears which require higher torque, this will increase consumption. Additionally, movement will be slow hence uneconomical fuel burning.

Is warming the engine necessary? Does it affect fuel consumption in any way?

Yes, warming up is necessary whenever starting from cold, the combustion chambers need certain temperatures to burn fuel efficiently.

Just like the human body functions well at a body temperature of 36 Degrees Celsius, the engine block temperatures are usually around 80 Degrees Celsius.

Consumption will be high in case operating at extremely low temperatures or overcooling of engine, this is the reason cooling fan is set to run intermittently and not continuous. Tear and wear on engine rotating parts also increases when the engine is cold.

However, overheating also has the negative effect of pre-ignition which may affect the smooth running of an engine.

Male drivers consume more fuel than women. True or false?

False. In either case, this depends on the drivers’ training and competency. If a driver does not engage right gears, don’t anticipate road situation and maintain necessary acceleration this will increase fuel consumption.

Drivers style and habits of driving, for example, rough driving, speeding unnecessary and vehicle mishandling are contributors to higher fuel usage.

Is there a correlation between braking and acceleration habits and the impact on fuel?

Yes, when a driver makes harsh acceleration, the engine revolutions go high increasing fuel usage. This is usually witnessed when someone is overtaking and doesn’t have enough space hence making engine RPM (revolutions per minute i.e. speed of the motor) to be extremely high.

Harsh braking is associated with inattention to road condition (failure to anticipate) and this means by the time a driver notices a situation to slow or stop, he may have been at higher speeds which could not take him anywhere. It’s basically a waste of fuel.

Air Conditioner while driving - what is its relation to fuel?

Car air conditioning uses a compressor that is engine-driven, this is an additional load hence straining on engine resulting in higher fuel uses.

The AC should only be used when very necessary otherwise you increase fuel usage.

Car servicing and fuel consumption; does a well-serviced car consume less fuel?

Yes, tear and wear in a car result in higher consumption. Well maintained parts will see a smooth-running, whenever we do car service this is meant to facilitate proper running.

For instance, whenever oil, oil filter, air cleaner and fuel filters are changed, they renew the engines optimal performance as opposed to lack of changing these parts.

Tyre inflation - It is perceived that you spend more fuel when you drive a car with low tyre pressure. Is that true?

Yes, whenever tyre pressure is low, the friction between the road and the tyres increases and therefore more traction effort is needed to overcome the friction in order to put the vehicle in motion.

Does driving with the windows open affect fuel consumption?

Yes. Vehicle body construction design takes care of aerodynamics to facilitate smooth vehicle penetration through air resistance.

Driving with windows open and travelling at high speeds, creates more air resistance and drags the vehicle hence more acceleration is required to overcome the drag.

What is the impact of weight in the car - (people or goods) on fuel consumption?

Every vehicle is designed with a particular capacity of load that is in relation to engine capacity. A vehicle needs torque and power to be able to move, whenever there is more load, the torque and power also need to increase and this increases fuel consumption.

Driving a vehicle that’s empty will consume less fuel than when it is loaded, change in load increases usage, overloading even increases further consumption other than increasing tear and wear.

Low tyre pressure can cost you more fuel. [iStockphoto]

What tips can you give on how to reduce fuel costs?

-Service your vehicle at required intervals

-Avoid harsh acceleration and harsh braking

-Anticipate and adjust to road traffic conditions

-Practice and actively use skills learned in a driving school

-Further, you can take Defensive Driving training

-Don’t compete on the road, practice a positive attitude

-Avoid overloading

-Employ competent drivers and train them regularly on refresher and Defensive Driving skills.

-Corporates can also implement a Fleet Management System that will monitor fuel consumption, driver behaviour e.g. harsh braking, harsh acceleration, over speeding among others

-Keep your tires inflated at the correct pressure

-Avoid lengthy warm-up idling

-Accelerate slowly and smoothly

-Avoid long engine idling – turn off the engine in case of a traffic jam or long waiting periods

-Use your air conditioner only when necessary – this causes an extra load to the engine

-Avoid stop and go driving – it wastes fuel

-Do not rest your foot on the clutch or brake pedal