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How are fuel consumption figures in car ads calculated?

How are fuel consumption figures in car ads calculated?

chitchatboy

Entry posted by chitchatboy ·

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blogentry-133713-0-74036400-1486373057_thumb.jpgREADER Mrs Frances Choo wrote in to askST how fuel consumption figures in car advertisements are arrived at, and if the method by which these figures are arrived at are consistent across makes and models.

Senior transport correspondent Christopher Tan answered.

 

Fuel consumption and carbon dioxide emission figures are calculated by vehicle manufacturers in a laboratory setting which purportedly mimics real-life driving conditions.

 

But actually, these tests rarely reflect real-world consumption.

 

The Japanese test cycle seems to be more representative of what motorists in a built-up city like ours experience than the European test cycle. Less is known about how reflective American and Korean test methods are of our driving environment but it would not be unfair to assume some discrepancy exists.

 

But how much fuel a car eventually consumes depends on many factors. Driving behaviour (aggressive and jerky, or gentle and smooth); load factor (number of people and things in the car most of the time); and road conditions (highway off-peak, or city peak) are the three top factors.

 

Having optimally inflated tyres and a well-maintained vehicle will improve fuel efficiency, too.

 

So, the same car driven by different people can have vastly different economy figures.

 

Having said that, most drivers here will not be able to replicate the consumption figures declared by manufacturers (especially European manufacturers), unless they drive on Malaysia's North-South Highway at a constant 90km/h.

 

Still, fuel consumption figures - which retailers are required by law to declare along with CO2 emission levels - provide consumers with a guide. But because there is no universal test cycle, it is somewhat difficult to compare consumption figures of cars from different countries.

 

It is easier to compare a Japanese car with another Japanese car, and a German car with another German car. But things get fuzzy if you were to compare a German car with a Japanese car. For example, a 2.0-litre Mercedes-Benz E200 has a declared consumption of 15.9km/L - making it more frugal on paper than a 1.6-litre Toyota Corolla Altis (15.3km/L). But in real life, the Corolla is likely to prove more economical here.

 

And generally, the further a car's fuel consumption is from reality, the same goes for its CO2 emission level.

 

So, it might be a good idea for consumers to look at what figures other drivers are getting. Or to read up on road-test reports published by The Straits Times, or a car magazine like Torque.

 

The following article is written by Christopher Tan, a Senior Transport Correspondent with The Straits Times.


7 Comments

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Watwheels

Different countries like the US, Europe and Japanese have their standards of testing.

example in Europe... http://www.dft.gov.uk/vca/fcb/faqs-fuel-consumptio.asp

 

How is the fuel consumption test conducted? 
  • The test is outlined in Directive 93/116/EC as amended by Regulation (EC) 692/2008, and provides results that are more than representative of actual average on-road fuel consumption than previous tests. There are two parts: an urban and an extra-urban cycle. The cars tested have to be run-in and must have been driven for at least 1,800 miles (3,000 kilometres) before testing.
  • Urban Cycle
    The urban test cycle is carried out in a laboratory at an ambient temperature of 20oC to 30oC on a rolling road from a cold start, i.e. the engine has not run for several hours. The cycle consists of a series of accelerations, steady speeds, decelerating and idling. Maximum speed is 31mph (50km/h), average speed 12mph (19km/h) and the distance covered is 2.5 miles (4km).
  • Extra-Urban Cycle
    This cycle is conducted immediately following the urban cycle and consists of roughly half steady-speed driving and the remainder accelerations, decelerations, and some idling. Maximum speed is 75mph (120km/h), average speed is 39mph (63 km/h) and the distance covered is 4.3miles (7km). 
  • Combined Fuel Consumption Figure
    The combined figure presented is for the urban and extra-urban cycle together. It is therefore an average of the two parts of the test, weighted by the distances covered in each part.

 

Question is what are you looking at in the brochure printed here in Singapore? Is it a combined figure? Comparing cars made from the different countries I mentioned earlier with different means of testing....is it a "fair" comparison? The driver factor, the road conditions, the grade of fuel used. How to make a meaningful conclusion? You don't. All I see are estimates.

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Paddie

I thought all cars in Singapore are certified by the NEA to the same standard, which is the European standard? Even a Honda Jazz fuel consumption and CO2 is based on EU standard, which is different from the Japanese standard that the writer talks about. Therefore all the figures for Singapore are indeed directly comparable.

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ER-3682

Last Saturday,Life motoring,reported the Subaru 1.6,getting 16L/100Km[6.25Km/L],how is that test carried out.?My Fairlady,even heavy footed still can get 6.5Km/L.

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Still2016

Can our in-house blog contributor contribute something from their own. It is often shown as

 

Written by ................

 

But in reality it is a cut and paste article.

 

 

I like to read person experiences. Thanks

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Sdf4786k

I supposed with this article, it puts an end to the constant compliant by owners on why the car consume so much fuel vs what is advertise during the First servicing of the car at the agent.

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Hydrocarbon

Different countries like the US, Europe and Japanese have their standards of testing.

example in Europe... http://www.dft.gov.uk/vca/fcb/faqs-fuel-consumptio.asp

 

Question is what are you looking at in the brochure printed here in Singapore? Is it a combined figure? Comparing cars made from the different countries I mentioned earlier with different means of testing....is it a "fair" comparison? The driver factor, the road conditions, the grade of fuel used. How to make a meaningful conclusion? You don't. All I see are estimates.

The main article write so much, but so much fluff. Yours, I get way more info from in much less words.

 

(y) <thumbsup!

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