Earlier this week, we reported on an influx of complaints from diesel owners who were required by law to permit Volkswagen to rectify their emission rigged engines. The consensus was that the company has not done a great job. If a veterinarian fixed a pet in the same manner that VW “fixed” these cars, you would probably put it out of its misery and then throttle the vet for butchering your now-ruined family companion.

Owners of the vehicles have complained of units lacking their former oomph, shuddering, stalling, and even being difficult to restart. While not every driver reported identical problems, the majority agreed Volkswagen had ravaged the engines’ ability to make power. At the time, nobody knew exactly how extensive the losses were. But, as the powerband-sapping solution closes in on North America, those numbers have come in.

Swedish researchers from the country’s preeminent motoring magazine, Teknikens Värld, conducted back-to-back testing of 10 cars from Skoda, VW, and Audi before and after the fix. The findings, at the very least, indicate Volkswagen Group may have broken its promise to returning the corrected cars in the same state as before. While some of the vehicles became thirstier and made more power, most became significantly less impressive. Engines saw up to a 10-percent decrease in performance with a new torque curve biased toward higher engine speeds.

Volkswagen assured customers that their cars’ performance would remain unaffected, but Erik Lehfeldt, the owner of Passat Alltrack tested by Teknikens Värld, said that’s not been his experience.

“I’m disappointed in Volkswagen. First, they cheat on the emissions purification and then they lie to the customers. They promised that the car would be exactly as before the fix, but that’s not true. My car is considerably weaker,” Lehfeldt explained.

Of the diesel motors that took part in the Swedish tests, the 1.6 liter TDI mills performed best after the fix. Researchers actually saw those vehicles produce extra power and torque. However, the curve in Lehfeldt’s Passat had shifted enough to make the vehicles feel lethargic at normal engine speeds. A pre-fix rating of 125 lb-ft of torque at 1,800 rpm transformed to a post-fix 118 ft-lb at the same engine speed.

Things were even worse in the 2.0-liter TDI cars. While a couple saw additions to peak horsepower, they were all down on torque and pulling-power tapered off far too early. A tested 2.0-liter Audi Q5 went from 266 lb-ft at 2,345 rpm to 247 ft-lb at 2,590 rpm. Interestingly, Audi announced it would be replacing the old Q5 powerplant with a new 2.0-liter direct-injection turbo unit just earlier today, showing its continued desire to distance itself from diesel-powered platforms. That’s likely a wise move as the company clearly doesn’t know what the hell it’s doing with them.

Here is your warning. If you were one of the precious few Volkswagen owners who opted out of the company’s diesel buyback program, now might be a good time to reconsider.