Volkswagen 'totally screwed up' over diesel emissions tests, US boss says

Volkswagen had rigged reports of diesel emissions for around 500,000 cars

President and CEO of Volkswagen Group of America Michael Horn attends the 2016 Volkswagon Passat Unveiling at the Duggal Greenhouse on September 21, 2015 (FilmMagic)

Volkswagen "totally screwed up" its emissions testing, the US boss of the German car company has said, as it emerges 11 million cars may have been affected with cheating software.

Michael Horn said: "Our company was dishonest with the EPA and the California air resources board, and with all of you, and in my German words, we have totally screwed up."

It emerged on Friday that VW had rigged reports of diesel emissions for around 500,000 cars. The company was ordered to recall half a million cars in the US.

By mid-afternoon trading on Monday, almost €15 billion had been wiped off the value of Volkswagen, dragging down the value of the DAX, a German stock market index.

Over the weekend, the Environmental Protection Agency in the US accused VW of skirting clean air rules and warned that it could face fines of more than $18 billion.

VW became the top selling car maker in the world in the first half of 2015, eclipsing Toyota, but there is no telling how a hit to its reputation will weigh on sales.

In a statement, Volkswagen chief executive said that that he would support the investigation by the German transport minister.

"I personally am deeply sorry that we have broken the trust of our customers and the public," Martin Winterkorn said.