Why your fuel consumption is worse than the official rating

South Africans are subjected to fuel costs that have climbed drastically over the last decade.

During 2019, the inland price of 95 octane petrol shot up from R14.01 in January to R16.30 in December, while the prices of 93 octane and diesel have also spiked.

The increase of R2.29 in 95 unleaded equates to a rise of 15.9%, more than three-times the average rate of inflation for the year.

Because of this, claimed fuel consumption is an important factor for potential car buyers.

However, the fuel consumption they get is often worse than what is indicated by the manufacturer.

Testing standards

To understand why there are discrepancies between the manufacturer’s claimed and real consumption numbers, it is important to consider the way they calculate a car’s claimed consumption.

The Automobile Association (AA) details the tests used to calculate the official consumption numbers used by manufacturers.

Carmakers previously used a 20-minute two-cycle testing model known as the New European Driving Cycle (NEDC), which was developed in the 1970s.

This process would involve simulating driving in city (urban) and highway (extra-urban) conditions to calculate how much fuel is used.

Three official figures can be extrapolated from these tests – urban, extra-urban, and “combined” (an average of the two aforementioned figures).

This standard has been replaced by a newer 30-minute five-cycle testing model called the Worldwide Harmonised Light Vehicle Test Procedure (WLTP).

This updated test takes the use of an aircon into account, covers a greater distance, uses higher speeds and a more dynamic driving cycle for increased accuracy.

As of 1 September 2018, all new car models are tested with the WLTP method.

Reasons for differences

MyBroadband spoke to the AA’s Layton Beard to learn why these numbers often differ from real-life consumption.

Aside from potential environmental factors that may contribute to differences in consumption, such as weather and road conditions, driver behaviour can result in significant variations in fuel consumption, he said.

These behaviours include:

  • Stopping and starting habits
  • Heavy and low engine revving
  • Sharp or gradual braking
  • Speeds driven
  • The prevalence of turning

“The tyres will impact on consumption, whether or not you tow, how often you use the aircon, if you drive with the windows open, the grade of fuel used, how many people in the car, the load of the vehicle, etc. There are many variables to fuel consumption,” Beard said.

Add to this the fact that these testing labs use fuels of different octane levels, and it’s easy to grasp that differences could exist.

The case of the Ford EcoSport

If a car owner in South Africa finds legitimate glaring discrepancies between claimed consumption and true fuel consumption, their options are limited.

In 2014, a Ford EcoSport 1.0T owner successfully challenged the company over an online advertisement that stated the claimed consumption figure as 5.7l/100km.

The complainant had recorded a figure of 8.6l/100km, a difference of a significant margin.

The Advertising Standards Authority (ASA) made a ruling that Ford South Africa’s advert did not sufficiently state that figures shown were only reachable in a controlled laboratory environment.

The ASA stated that “while a reasonable person would understand that he/she might not achieve those exact results, the expectation would be that they are still in the vicinity of what might be expected.”

The finding, however, was made based on the lack of information in the ad and did not include a ruling on the issue of actual consumption.

Manufacturers clearly add a disclaimer in car brochures and on stickers that are sometimes found on the cars which stipulate that the claimed figures were taken from the above-mentioned tests.

Consumer options

In cases where a vehicle fault or false claims from the manufacturer result in exorbitantly high fuel consumption, South African consumers have limited options.

Since South Africa has no consumption testing laboratories of its own, proving an issue could be daunting and expensive.

According to Beard, the only way to disprove the claimed consumption is to have the car sent back to the same testing centre.

“Realistically, the only way a driver can ensure his/her consumption is exactly the same as what is stated on the sticker in the vehicle or in the brochure is to have that specific vehicle tested in the same lab, under the same conditions,” Beard said.

“Fuel consumption is going to differ from driver to driver for a variety of factors, and this is the only scientific way of making this determination,” he added.

AA recommendations

Because of these factors, Beard said car buyers should not consider claimed consumption numbers as a perfect measure of what should be expected.

“Use the fuel consumption indicated by the manufacturer as a guideline only, and determine your own consumption over a period of time.”

To do this, Beard recommended keeping a driving logbook to assess your car’s true consumption and adjust behaviour that may lead to excessive fuel use.

“This will give you a good indication of how much your fuel consumption is and what you are paying for fuel over a period of time. A logbook should also record the amount of fuel you put in your tank, and what it costs per litre at that specific time,” Beard explained.

This could provide essential information on your car’s performance and your driving.

“Knowing more about your vehicle and its consumption gives you a better idea of how your car is performing, and how you are driving. This may also prove to be a good early warning system if there is a problem with the vehicle.”

Beard also emphasised safety as a key focus for any vehicle purchase.

“Importantly it’s vital to check if your vehicle has a local NCAP rating through the #SaferCarsforAfrica programme.”

“Look at the safety features instead of the luxury features. So look for ESC and ABS, instead of Bluetooth sound system and mag wheels. Look at whether the vehicle will be fit for the purpose it is being purchased,” he said.

Wesbank Fuel Economy Tour figures compared

As an example of possible differences in fuel consumption, MyBroadband compared claimed figures with the findings of the Wesbank Fuel Economy Tour.

WesBank recently held the inaugural run of the event, which tested 40 vehicles on a five-day route from Johannesburg to Cape Town to measure real consumption.

In most cases, the average combined consumption of the tested vehicles measured less than the manufacturer’s claimed figure.

It should be noted that in the cases of cars like the Fiat Tipo and Mahindra XUV 300, the teams driving the vehicles were penalised severely, which likely significantly affected their final scores.

Judging by this comparison, it would appear that most manufacturers take a rather conservative approach to consumption figures, and that the car models in this table should meet the expectations of potential car owners, bar any technical malfunctions.

The table below shows a comparison between the advertised claimed fuel consumption and the final results of Wesbank’s Fuel Economy Tour.

Position Vehicle make and model Manufacturer’s claimed consumption (l/100km) Fuel Economy Tour average combined consumption (l/100km)
1 Renault Captur PHZ Dci DYN 3.6 4.73
2 Toyota Aygo 4.3 4.83
3 Nissan Qashqai 1.5 Turbo Diesel 4.2 4.85
4 Renault Duster DCJ EDC 4×2 Techroad 5.1 5.07
5 Suzuki Baleno 1.4 GLX MT 5.1 5.08
6 Suzuki Ignis 1.2 GLX LMT 4.9 5.09
7 Suzuki Swift 1.2 GLX MT 4.9 5.11
8 Mahindra XUV 300 1.5D W6 4.8 5.20
9 Ford Fiesta 1.0T 5.2 5.21
10 Mahindra KUV100 1.2D K6 4.4 5.22
11 Nissan Micra Turbo Visia 5.1 5.26
12 Suzuki Vitara 1.4 GLX MT 5.8 5.34
13 Ford Kuga 1.5 TDCi Trend 6MT FWD 6.2 5.39
14 Renault Kwid Climber 4.7 5.41
15 Suzuki Swift Sport 1.4T MT 6.1 5.59
16 KIA Picanto 1.2 Smart 5.0 5.66
17 Suzuki Vitara 1.6 GL 6.0 5.80
18 Suzuki Ertiga 1.5 GLX MT 6.2 5.84
19 Lexus UX Hybrid Model unavailable 6.03
20 Fiat Tipo 1.3 Multi-Jet Easy 4.4 6.05
21 Hyundai Santa Fe 7.5 6.17
22 KIA Sorento LX 9.6 6.22
23 Honda HRV 1.8 Elegance 6.8 6.34
24 Hyundai Venue Model unavailable 6.34
25 Honda Civic 1.5T Sport 5.9 6.35
26 Mahindra XUV 300 1.2T W8 4.8 6.42
27 Hyundai Creta Model unavailable 6.69
28 Ford Ranger 2.0 SiT DC XLT 4 x 2 AT 7.2 6.82
29 Mitsubishi Triton 4 x 2 M/T 7.1 6.85
30 Toyota Hilux DC 2.8 L50 RB Man 7.6 6.94
31 Hyundai Tucson 2.0D 7.9 6.96
32 Nissan Navara 2.3D DC SE/LE 6.3 6.97
33 Toyota Hilux DC 2.4 SRX RB Man 7.1 6.98
34 Renault Duster 1.6 EXP MY19 7.0 6.99
35 Toyota RAV4 2.0 GX Man 6.8 7.04
36 Mitsubishi ASX 2.0 M/T 7.6 7.22
37 Mitsubishi Eclipse Cross 4 x 2 7.9 7.34
38 Mahindra Pik-Up 2.2D S6 D-Cab 7.9 7.69
39 Mitsubishi Pajero Sport 4 x 2 8.0 7.92
40 Honda BRV 1.5 Trend Comfort 6.3 8.24

Now read: “Blue Light Protocol” no longer safe for South African drivers

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Why your fuel consumption is worse than the official rating