Updates to the millions of Volkswagen TDI diesel cars that turned out not to meet European emission regulations were supposed to be well underway by now.

German authorities had signed off on the modifications—software updates and for one group of engines, a new plastic insert to alter incoming airflow—and VW began the updates with its Amarok pickup truck.

But those updates have stalled, amidst reports that while the cars comply with European test procedures, they continue to emit much higher volumes of nitrogen oxides than legally permitted when operating in real-world conditions.

DON'T MISS: European VW diesel update halted, lower fuel economy at fault?

Now, the Swedish technology newspaper Ny Technik has published an interview with Per Öhlund, investigator at the Swedish Transport Agency, that sheds some light on the current state of affairs.

As translated by a helpful reader, Öhlund explains that the German magazine Auto Motor und Sport tested a modified Volkswagen Amarok pickup truck and found it to emit the same amount of nitrogen oxides in road use as it had before the modifications.

Volkswagen Amarok Canyon concept

Volkswagen Amarok Canyon concept

The Amarok with updated software performed identically to an unmodified version, used slightly more diesel fuel than the comparison vehicle, and continued to emit 1.5 grams of nitrogen oxides per kilometer—far above the Euro 5 emission limit of 0.18 g/km.

The German regulatory agency KBA (Kraftfahrt Bundes-AMT) approved VW's proposed modifications, which apparently brought the Amarok into compliance with emission tests performed under the New European Driving Cycle (NEDC) protocols.

ALSO SEE: VW diesel scandal now 6 months old; what have we learned?

Historically, manufacturers in Europe paid third-party testing companies to test their new vehicles' emissions, and submitted those results to the regulatory agencies in individual markets.

Those companies obviously had an incentive to make sure their clients' cars passed, and some reportedly removed door mirrors, taped over body seams, and took other measures that made the tests less and less realistic.

2012 Volkswagen Passat TDI Six-Month Road Test

2012 Volkswagen Passat TDI Six-Month Road Test

European consumers' dismay and anger over associated fuel-economy ratings that can be as much as 30 percent too optimistic had been brewing even before the Volkswagen diesel-emission scandal broke last September.

Regulators and automakers together are working to finalize new testing regimes that may include on-road testing, but those won't take effect for at least two or three years.

Meanwhile, Volkswagen's update program for Germany and other European countries—where the bulk of the 11 million non-compliant diesel vehicles were sold—remains stalled after just 500 Amarok pickups have been modified.

CHECK OUT: Can VW, agencies meet April 21 diesel-fix deadline? EPA head not sure

In North America, tomorrow is the deadline for Volkswagen, the U.S. EPA, and the powerful California Air Resources Board to reach agreement on a plan to modify 580,000 diesel vehicles sold by VW, Audi, and Porsche since 2008.

Those include vehicles with two different 2.0-liter four-cylinder turbodiesel engines and a 3.0-liter V-6 diesel as well.

Whether the company and regulators can reach agreement by tomorrow remains unclear; EPA administrator Gina McCarthy indicated two weeks ago that she wasn't sure if that would happen on time.

[hat tip: Tomas Nylen]


Follow GreenCarReports on Facebook and Twitter.