During televised questioning from a US congressional committee, Michael Horn, the CEO of the Volkswagen Group's American arm, admitted that the upcoming fix will have an impact on performance, although he seemed to imply that the hit will not be that significant.
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Frank Pallone, a member of the House of Representatives energy and commerce oversight and investigations committee, and a representative from New Jersey, asked if the upcoming fix for US market EA189 diesel engine cars with the emissions testing defeat device would have an impact on performance or fuel economy.

Horn replied: "My understanding is that if that if we correct the nitrogen oxide emissions to the emissions standard, the customer will get the MPG [stated] on the Monroney label ... one or two miles per hour might be missing, but this is something, of course, which we will share agencies. But my current understanding is that the customer will keep the Monroney miles per gallon."

Pallone countered customers might reasonably expect compensation if their cars' fuel economy or performance is affected by the fix.

Volkswagen's American chief stated: "I said that to my current understanding, in achieving the emissions standard the Monroney label miles per gallon will be achieved [but] there might be a slight impact on the performance. And this is naturally not only the discussions with the agencies but, of course, we will look into compensating our customers, and if it would be significant differences this will be part of the discussion."

At the end of Pallone's allotted time, he questioned Horn about what the company will do about the excess NOx pollution emitted by the roughly 482,000 defeat device-equipped Volkswagen and Audi models sold in the USA.

In response, Horn answered: "I think first of all, there's many different studies, I would like to go back to the EPA, to what they said. I think it will be part of the discussion. I would also like to put out that if you look at 100 percent of nitrogen oxide emissions in the US, the car and truck industry is having five percent. Our group here in the US has four percent of the five percent, which is 0.2 percent. Out of this, 20 percent is TDI, which is 0.05 [percent] and we can multiply this.

"Which is not belittling this, and this is clearly unacceptable, but within this context the discussion will come up and will need to be addressed."


At another point during his three hour appearance in front of the committee, Horn outlined his belief that the call to install software to help its EA189 diesel engined cars fraudulently pass emissions test "was not a corporate decision", sheeting the blame onto "a couple of software engineers".

Up to 11 million vehicles worldwide from Volkswagen, Seat, Skoda and Audi have been caught up in the so-called "dieselgate" affair.

97,621 of those cars were sold in Australia. The Volkswagen Group has setup websites so owners can see if their vehicles are affected.

Last weekend, Volkswagen Australia confirmed that it would halt sales of its 1.6- and 2.0-litre EA189 diesel cars, while Audi Australia said it had temporarily withdrawn cars with 2.0-litre EA189 TDI engines from sale.

All affected vehicles will be recalled, but the various fixes aren't expected to be ready until 2016. The company currently believes that some cars can brought into compliance with software alone, while others will also require hardware changes.