As Germany moves towards reducing car emissions, cities such as Frankfurt are considering banning older-model diesels from their streets or select roads, while others, like Hamburg, have already done so.

Yet, the state government is currently opposing a diesel ban in Frankfurt, looking to appeal a court decision that would make older cars unfit to roam the city’s streets starting next February, reports Automotive News Europe.

“Planned measures, such as deploying electric buses, building better cycle paths and more park-and-ride offerings would, in practice, have the same effect as a general driving ban,” said Hesse Prime Minister, Volker Bouffier, a member of Chancellor Angela Merkel’s Christian Democrats party.

The German government has yet to decide whether or not to force automakers to retrofit older models with exhaust-cleaning systems in order to make them less of a threat to the environment, as well as to people’s health. Statistically speaking, about a quarter of Frankfurt’s cars would be affected if the court-ordered ban is enforced.

The initial plan was to first ban Euro 4 diesels and Euro 1 and 2 petrol-powered cars from the city, followed by a ban of Euro 5 diesels starting next September – while Euro 6 ones would be exempt from the ban.

According to environmental group Deutsche Umwelthilfe, banning diesels is the only way for Germany to meet the European Union’s clean air rules, which stipulate that nitrogen dioxide pollution shouldn’t exceed 40 micrograms per cubic meter of air.