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August 6, 2019
Many tales of epic fuel consumption drives in South Africa
August 6, 2019

Fuel economy labelling

The South African automotive industry, in conjunction with the Department of Minerals and Energy, introduced a standardised fuel economy and CO2 emission testing and labelling system for new passenger cars sold from July 1, 2008. The labels must be displayed on the windscreen of the vehicle at the point of sale.

The system used to obtain the fuel consumption and emission figures printed on the labels is based on that used in Europe for many years. Known as the New European Driving Cycle (NEDC) and dating back originally to the 1980s. This test procedure involves all the various models being submitted to the testing authorities by the manufacturers and then they are evaluated in a laboratory under the same speed, acceleration and braking cycles carrying the same load and using the same fuel.

However, over the years a great deal of controversy has arisen over the validity of these tests, with certain manufacturers having been found guilty of installing default systems in their cars that can identify when the specific vehicle is being tested for fuel economy and emissions and then adjust the engine settings to pass the test.

New test procedures introduced

For many years’ motorists have been frustrated by being unable to achieve manufacturers’ claimed fuel consumption figures in real world driving. So, with this in mind as well as the above-mentioned testing scandals, a new system has been introduced from September 2018.

The far more complex Worldwide Harmonised Light Vehicle Test Procedure (WLTP) laboratory test replaces the previous, outdated test procedure which was known as the New European Driving Cycle (NEDC) and came into use in the 1980s.

The new procedure, while still laboratory based, uses real-driving data gathered from around the world so that it better matches everyday driving performance. It also measures carbon dioxide emissions, which is very important in big cities due to increasing traffic congestion. Some cities are even planning to ban vehicles powered by internal combustion engines to cut the amount of noxious gases in the air.

Even though the new test is a more realistic representation of conditions encountered on the road than the previous one, on-road performance in everyday driving will still be different due to varying driving styles which cause big variations in fuel consumption with some drivers accelerating faster and braking more heavily than others.

More realistic testing conditions with WLTP system

  • Higher average and maximum speeds.
  • A wider range of driving situations (urban, suburban, main road and motorway)
  • More dynamic driving cycle with representative accelerations and decelerations
  • Higher average speed and maximum power driving simulation
  • Longer test distances.
  • More realistic ambient temperatures, closer to the European average.
  • Effect of optional equipment, such as air conditioning on fuel consumption and CO2 emissions is measured.

 

Old test / New European Driving Cycle (NEDC) New test / Worldwide Harmonised Light Vehicle Test Procedure (WLTP)
Test cycle Single test cycle Dynamic test cycle more representative of real driving
Cycle time 20 minutes 30 minutes
Cycle distance 11 km 23.25 km
Driving phases 2 phases – 66% urban, 34% non-urban 4 more dynamic phases – 52% urban, 48% non-urban
Average speed 34 km/h 46.5 km/h
Maximum speed 120 km/h 131 km/h
Influence of optional equipment Impact on CO2 and fuel performance not considered Additional features (which can differ per car) are considered
Gear shifts Vehicles have fixed gear shift points Different gear shift points for each vehicle
Test temperatures Measurements at 20 – 30°C Measurements at 23°C, CO2 values corrected to 14°C

 

Labelling cars in South Africa post the introduction of WLTP

Labelling on new cars in South Africa will continue to be based on the NEDC system, with figures for cars tested according to the WLTP system being converted to those comparable to consumption and emission figures obtained using the NEDC system.