Svenja Schulze (SPD), the German minister for the environment, has urged her own government on Monday to make so-called "hardware" updates for diesel vehicles available to motorists as soon as possible.

A spokesperson for Schulze told press in Berlin that hardware updates offered the most effective solution to improve urban air quality. The comments were shortly before the Berlin Administrative Court opened consultation on whether such diesel driving bans can be avoided in the German capital as a means to reduce nitrogen oxide (NOx) pollution.

Together with several non-governmental environmental organizations and the Federal Environmental Agency (UBA), Schulze has been a long-standing advocate of offering technical retrofitting in response to the diesel emissions scandal and requiring carmakers to foot at least part of the bill for the measures. Following closely-watched cabinet deliberations over how to prevent driving bans, chancellor Angela Merkel's (CDU) ruling "grand coalitions" recently presented the outlines of a policy package which for the first time made concrete provisions for hardware upgrades.

The officially-titled "concept for clean air and the protection of individual mobility in our cities" is aimed specifically at areas with high NOx pollution levels. Aside from contested hardware upgrades, the policy package includes financial incentives for diesel vehicle owners to buy a new, supposedly cleaner, cars. According to the federal government, 1,4 million motorists will benefit from the measures.

Schulze's spokesperson argued on Monday that the priority of the federal government in preventing looming driving bans should now be to ensure that hardware upgrades are conducted swiftly. However, among automotive industry companies only the Volkswagen and Daimler groups have so far voiced their support for the measures.

Additionally, Volkswagen has made its own support for the most contentious part of the policy package conditional on the ability of Merkel to ensure the participation of all carmakers in the retrofitting programs. In spite of ongoing investigations by judicial authorities, no automotive company in Germany has yet been found guilty of falsifying NOx emissions levels from diesel vehicles with illicit motor software. Until they are convicted, the federal government hence relies on the voluntary cooperation of carmakers in offering customers hardware upgrades.

The UBA has estimated that diesel cars are responsible for more than 50 percent of NOx emissions in Germany. NOx levels currently exceed binding limits set in EU clean air legislation in several major German cities.