"We are confident we will find an acceptable solution," VW brand chief Herbert Diess said at a press conference at the Consumer Electronics Show in Las Vegas, Nevada.

In an interview with media agency, Diess said fixing older VW cars equipped with 2.0-liter diesel engines will be more difficult than bringing more recent models into compliance.

"The intrusion into the car will be quite significant," Diess said of the older models. Some US regulators and lawmakers have said VW may have to buy back older models. Diess didn't say whether VW is discussing that, but said he is optimistic that an agreement with US regulators will be reached soon.

"It's a very constructive dialogue," he said.

Diesel technology will still play an important role in VW's future product strategy, Diess said. "Diesel still has a future in some segments," including in sport utility vehicles, "and in some markets it will be a must," he said. Europe will still be a major diesel market in the next decade, Diess said.

Volkswagen has admitted it installed software in certain diesel models sold in the United States, that allowed the cars to pass government emissions tests, but then emit nearly 40 times the allowed levels of pollutants on the road.

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