The Germany's Federal Motor Transport Authority originally allowed people from VW to do the testing, but it then replaced them with independent engineers. VW claims the switch pushed back the evaluations' end by a week or two, according to Automotive News Europe.
In contrast, German media reports claim that the tests showed the fix caused increased fuel use for the Passat, but VW said the allegation was speculation. "We have to guarantee that noise and especially CO2 emissions are exactly the same as before the fix," a company spokesperson told Automotive News Europe.
VW had previously said that European vehicles with the 2.0-liter TDI, like the Passat, only required a software update. When it announced the diesel repairs, the German automaker said the goal was to meet emissions standards without adverse effects on fuel economy or performance.
Repairs haven't yet started for any VW Group diesel vehicles in the US. A judge gave the automaker until March 24 to outline an acceptable fix for the 2.0-liter engines, but the company missed that date. It now has until April 21 to figure something out. The head of enforcement at the California Air Resources Board believes that full compliance might not even be possible. CARB also continues to evaluate the proposed fix for the 3.0-liter V6 TDI.