"First, they cheat on the emissions purification and then they lie to the customers," says owner Erik Lehfeldt.

Confirming anecdotal reports, tests of Volkswagen's 'fixed' vehicles in Europe has revealed drastically altered torque curves for most models.

Swedish auto magazine Teknikens Värld performed a series of before-and-after experiments with 10 diesel models including the Skoda Yeti, the Audi Q5 and the VW Caddy, Passat CC, Golf, Passat Alltrack and Sharan, among others.

"Some cars have gained power and have a higher fuel consumption, but most cars have lost performance," the report says. "Both torque and power have decreased after Volkswagen's fix. The loss is as much as ten percent and in addition to that the torque curve has shifted."

The Alltrack lost 13 horsepower and seven pound-feet of torque. The peak losses do not seem like much but, perhaps more importantly, high torque is only available at higher rpm.

"It was slightly slower and the alertness I experienced before was completely gone," said Teknikens Värld test driver Ruben Börjesson. "At motorway speed and on regular country roads however, I couldn't feel any difference. Starting, stopping and slow-moving queues made the car feel lazy."

VW Sweden spokesman Marcus Thomasfolk claims the German KBA testing authority approved the modifications "and told us that there has been no adverse impact," and only 0.1 percent of Swedish customers have complained.

"We still have yet to learn the details of Teknikens Värld's test and the method used and look forward to doing so in order to comment more specifically," he added.