The manipulation of carbon emissions data has been going on at Volkswagen since 2013 because of extreme reduction targets set by former CEO Martin Winterkorn, according to German newspaper reports.
According to German newspaper Bild am Sonntag, several Volkswagen engineers have admitted tinkering with tyre pressure as well as mixing diesel with motor oil to reduce fuel consumption in order to achieve lower emissions in tests.
"Employees have indicated in an internal investigation that there were irregularities in ascertaining fuel consumption data,” said a Volkswagen spokesman. “How this happened is subject to ongoing proceedings,” he said, but declined to comment on the revelations by Bild.
According to Bild, Winterkorn declared at the Geneva auto show in March 2012 that VW wanted to reduce its CO2 emissions by 30 per cent by 2015 and the engineers did not dare to tell him that this would be difficult to achieve.
Winterkorn resigned in September after the US Environmental Protection Agency revealed the German car maker has been cheating in nitrogen emissions tests in the US using software known as the defeat device. The technology enabled the cars to detect when they were being tested and turned on systems to minimise the emissions. As running those systems continuously would have a negative impact on performance and fuel consumption, Volkswagen only used these emission-scrubbing systems in testing. As a result, the actual nitrogen oxide emissions were up to 40 times above legal limits.
In addition to the nitrogen oxide cheating that might, according to some estimates, cost Volkswagen some $38bn (£25bn) on fines, refits and lawsuits, the car maker also admitted last week that about 800,000 of its vehicles sold in Europe produce more carbon emissions and consume more fuel than officially claimed. The firm said it will pay compensation to the owners for the increase in taxes that would affect them as a result of the higher emissions.
To decrease the carbon emissions during measurements, the engineers were reportedly inflating tyres up to the pressure of 3.5 bar and mixed motor oil with diesel to make the engines run more smoothly and use less fuel.
VW is conducting an internal investigation into the handling of all pollution-related issues and has encouraged its employees to come forward with information saying it won’t prosecute regular staff for misconduct. High-level managers would still be held accountable, a person familiar with the matter said.