Fuel consumption of Volkswagen diesel vehicles increased by 14% after repairing exhaust system

According to foreign media reports, an emissions study commissioned by the Australian Automobile Association (AAA) found that an affected Volkswagen diesel car has increased its use of diesel by 14% after being recalled for repair of the exhaust system.

This real-world test was conducted in cooperation with the International Automobile Federation. The purpose was to quantify the performance changes of recalled vehicles after updating the software.

In 2015, Volkswagen revealed that its 11 million diesel vehicles were sold with cheating devices. When the vehicles were tested, they could change the performance of the vehicles and improve the emission test results. After this, the public began to recall these affected vehicles and repair the discharge system.

At the end of 2016, AAA commissioned research institute ABMARC conducted two tests on an affected Volkswagen. One test was before the vehicle was recalled; the other was started immediately after the recall.

The test results showed that after the 2010 recall, the Euro 5 VW Golf used an average of 7% (0.5L/100km) more fuel. 2% more fuel is used in urban areas; 7% more fuel is used on rural roads; 14% more fuel is used on highways.

Tests have shown that the emissions of nitrogen oxides, carbon monoxide and particulate matter have been reduced after recalling vehicles for repairs. However, tests conducted in a real driving environment show that nitrogen oxide emissions are still 4.11 times the laboratory limit.

The purpose of this study was to determine the effect of system restoration after vehicle recall. The method used is to compare the pollutant emissions in the real environment before and after the recall with the relevant laboratory limits; compare the fuel consumption of the vehicle in the real environment with the official released figures.

The results show that the public may have found a good repair program to reduce the emission of toxic nitrogen oxides, but this also leads to increased fuel consumption of vehicles. The test results also show that after the recall, the vehicle's power and torque slightly increased. The test results further support the AAA initiative to conduct real-world testing in Australia.

AAA launched a research project to test 30 Australian cars on Australian roads using Australian fuel oil. Subsequently, AAA strongly recommends the launch of a real-world emission test program.

The Australian Real Environmental Testing Program will enable consumers to make more informed purchase decisions and enable policymakers to monitor their policies to reflect the true situation. AAA believes that it is meaningless to introduce more stringent vehicle emission standards in the laboratory. It is the most important for consumers to master the performance of vehicles under real conditions.