Volkswagen 'dieselgate' fraud: Timeline of a scandal

As Volkswagen faces the wrath of car owners in a mass 'dieselgate' lawsuit on its home turf, here's a look at how emissions cheating was uncovered and the fallout for the auto giant.

A group of researchers in the United States at the University of West Virginia discover that certain Volkswagen (VW) cars emit up to 40 times the permissible levels of harmful nitrogen oxide when tested on the road.

In September, the United States Environmental Protection Agency finds Volkswagen of duping diesel emissions tests by using cheat devices.

In the same month, VW admits using software to reduce emissions during lab tests in over 11 million diesel engines worldwide.

As shares plunge by 40 per cent after the revelation, Chief Executive Martin Winterkorn steps down and says that he knew nothing.

In the aftermath of the revelation, VW announces a net loss, its first in 20 years and agrees to pay $14.7 billion in buybacks, compensations, and penalties in a mammoth settlement with US authorities.

The deal, which covers 2.0 litre diesel engines only, includes cash payouts for nearly 500,000 US drivers.

In September, the first VW investors file lawsuits in a German court seeking billions in damages.

They accuse the automaker of failing to communicate about the crisis in a timely way.

The European Commission launches legal action against seven EU nations including Germany in December for failing to crack down on emissions cheating.

Volkswagen pleads guilty to three US charges including fraud and agrees to pay $4.3 billion in civil and criminal fines in January.

As part of the plea deal, VW signs up to a "statement of facts" in which it admits that the cheating dates back to 2006, but it remains unclear how much the top brass knew about the scam.

In February, car parts maker Bosch, which supplied elements of the software, agrees to pay nearly $330 million to US car owners and dealers but admits no wrongdoing.

VW says it will pay at least $1.2 billion to compensate some 80,000 US buyers of 3.0 litre engines as well as buying back or refitting their vehicles.

VW executive Oliver Schmidt, who was arrested while on holiday in Florida in December, is sentenced to seven years in jail.

Volkswagen roars back to profit after record sales in 2017.

A German court paves the way for cities to ban the oldest diesel from their roads to combat air pollution.

VW Brand Chief Herbert Diess hastily replaces CEO Matthias Mueller after he too lands in prosecutors' sights.

In June, VW agrees to pay a one-billion-euro fine in Germany, admitting its responsibility for the diesel crisis.

The scandal has now cost the group over 27 billion euros.

Audi also agrees to pay a fine of 800 million euros.

In January, four Audi managers are charged in the United States by watchdog SEC.

Later, Winterkorn and four other managers are charged with "serious fraud" as well as unfair competition and breach of trust.

In May, Porsche agrees to pay a fine of 535 million euros, following which, Stadler and three former Audi managers are charged with fraud.

On September 24, Present VW Chief Herbert Diess, supervisory board chairman Hans Dieter Poetsch and Winterkorn are charged with market manipulation.