BERLIN, Aug. 15 (Xinhua) -- The non-governmental German Environmental Aid (DUH) group has accused policymakers and carmakers on Wednesday of making half-hearted attempts to lower nitrogen oxide (NOx) emissions caused by diesel vehicles in Germany

DUH President Juergen Resch told press that urban air quality would only improve again in the country once a commitment was made to conduct more comprehensive "hardware solutions" to modify diesel motors.

Resch said that emissions testing by his organization had showed that Volkswagen vehicles which had undergone software treatments in the wake of the diesel emissions scandal continued exceed regulatory limits set by the European Union (EU).

German carmakers have refused hardware upgrades so far on the grounds that they would be too costly, volunteering to offer motor software updates for more than 2.8 million diesel vehicles instead. However, Resch argued on Wednesday that the costs associated with more effective technical changes could easily be shouldered by the highly profitable automotive industry.

According to DUH, quick-fix technical upgrades could be completed for as little as 1,500 per vehicle. "It is possible and would not endanger jobs", Resch said. By contrast, he criticized the measures offered by carmakers as "Mickey-Mouse software upgrades" which failed to tackle the problem at hand.

So far, German Chancellor Angela Merkel's (CDU) coalition government has shown leniency towards economically-significant national automotive industry on the issue. Merkel's cabinet has debated for several months whether technical diesel motor upgrades constitute a feasible alternative to software upgrades.

The chancellor and Transport Minister Andreas Scheuer (CSU) publicly side with carmakers, while Minister for the Environmental Svenja Schulze has repeatedly demanded mandatory hardware upgrades as well. In the meanwhile, some major German cities like Hamburg and Stuttgart have already grasped an opportunity offered in a landmark court ruling by the Federal Administrative Court to unilaterally impose driving bans on diesel vehicles as a means to lower NOx emissions.

The Federal Environmental Agency (UBA) estimates that diesel cars are responsible for more than 50 percent of harmful nitrogen oxide emissions in the Germany. NOx levels currently exceed binding EU limits in several of the country's cities, prompting the Commission to file a lawsuit against the federal government at the European Court of Justice (CJEU).

Speaking to press on Wednesday, DUH President Resch urged Merkel to take a firmer stance on carmakers by forcing them to pay for technical diesel upgrades or take back vehicles which were installed with illicit defeat devices to understate their actual emissions levels.

"We expect the federal government to either enable citizen to access technical upgrades of manipulated vehicles which are paid for by the producers, or to return their vehicles to the producers in exchange for the original purchasing price -- just like authorities in the United States already have", Resch said.