On fuel consumption


carHave you noticed that your new car uses up more fuel than the manufacturer said it would? That does not mean that you are a bad driver. Motorists around the world know that the fuel consumption figures quoted by manufacturers usually (but not always) bear no relation to the real world.


Fuel consumption figures are calculated in a laboratory, under carefully controlled conditions that are very different to the prevailing conditions of driving. When the kilometre per litre ratio is tested in the laboratory, nothing is left to chance. Carmakers have perfected the art of lowering fuel use (and thus carbon emissions too) by resorting to the measures that include: tyres with extra traction; very smooth driving surfaces; taping over door cracks and grills to prevent wind resistance; switching off additional features such as air conditioning; driving the vehicle in high temperatures; and so on.


An international report puts the discrepancy between lab and real fuel consumption at about 25%. Some reviews published in car magazines say that the rule of thumb is to add 10% to the manufacturer’s figures for petrol engines and 20% for hybrids.


Since fuel consumption depends on numerous factors, ranging from climatic conditions and the condition of the car to loads carried and driving styles, there will always be some discrepancy; the worrying trend is that the discrepancy between the lab and real life fuel consumption is becoming bigger as years go by, not smaller.


So, if you are in the market for a new car, don’t go only by what the manufacturers say about the kilometres per litre ratio; rather, read the reviews and listen to word-of-mouth. By the way, if you happen to hear that some cars use less fuel than the manufactures claim they do – don’t write off such testimony as a fairy tale; this has been known to happen in real life.


Further reading:


The 10 Most Fuel Efficient Cars in South Africa

15 Ways to Save on Petrol