Independent Australian emissions study "flawed", says VW

Volkswagen Australia has vehemently rejected an Australian study that found its vehicles consumed more fuel after being recalled as part of the controversial 'dieselgate' emissions scandal.

The Australian Automotive Association (AAA) study was commissioned last year using a diesel-powered 2010 Golf 2.0 TDI - a vehicle that was subject to sweeping recalls after Volkswagen was found to have deliberately tampered with emissions testing software.

It took laboratory and real-world samples from the Golf before and after it received a software update from the manufacturer. Research group ABMARC, found that fuel use increased by as much as 14 per cent following the recall 'fix'.

The AAA claims the vehicle also emitted up to four times as many oxides of nitrogen (NOx) as the accepted laboratory limit.

However, Volkswagen Australia described the AAA's testing methodology was "flawed".

"Data recorded published by the AAA highlights glaring inconsistencies in the methods applied to testing a 2010 Volkswagen Golf Wagon," the company said in a statement.

The AAA's findings, which included city, country and freeway driving, showed the car used an average of seven per cent more fuel after the fix. Fuel consumption was two per cent higher in urban driving and 14 per cent higher on the freeway.

The final page of the AAA report exposes some disparities in the before and after testing. The original test was performed in dry conditions, according to the AAA, while the follow-up procedure was undertaken in cooler conditions and "light rain".

Furthermore, the AAA's reports says the test vehicle stopped on 27 occasions during its pre-recall test as opposed to 37 stoppages post-recall, some eight days later.

The post-recall "warm" test ran for 97 minutes -- five minutes more than the pre-recall test, the AAA said.

Volkswagen Group Australia managing director Michael Bartsch lamented the AAA's testing procedure.

"While the PEMS testing procedure used by the AAA may in principle be appropriate for testing emissions of nitrogen oxides, due to the high PEMS tolerances of ±10%, it is simply not suitable for testing fuel consumption and CO2 emissions," he said.

"Furthermore, major flaws which render the tests wholly unfit for purpose included substantial variations in the test runs and atmospheric conditions both on the same vehicle and different vehicles and even the performance of different vehicles being compared."

Volkswagen has recalled more than 100,000 vehicles in Australia as part of the dieselgate scandal, which first broke in 2015.

The AAA's study of this subject is not the first. It follows similar reports from major motoring organisations in Germany, Austria and Switzerland.

Bartsch called into question the timing of the AAA's study, which coincides with dieselgate class actions and a court battle between Volkswagen Group Australia and the Australian Competition and Consumer Commission.

"The so-called new test results are not new and were published by AAA early 2017 and sank without a trace," Bartsch said. "This is cynical opportunism based on the timing of an important trial in the Federal Court."

"As far as VW vehicles are concerned, on-road testing by reputable motorist's organisations in Germany, Switzerland and Austria show the opposite results to those arrived at by the AAA.

"The differences between laboratory tests and on-road testing results are well known and the ACCC has worked with all automobile manufacturers on approved wording, which Volkswagen Group members use in Australia, to ensure that this is properly disclosed to consumers."

The AAA is pushing for real-world fuel testing to be made mandatory in Australia, similar to measures being implemented in Europe.

Bartsch advocated Volkswagen as "an enthusiastic proponent" of such measures.