Transport ministers from Germany, Italy, the Czech Republic, Poland, Portugal, Romania, Hungary and Slovakia on Monday discussed their push to change proposed European Union Euro 7 emissions limits.
The Euro 7 law, which EU countries and lawmakers will start negotiating this year, would tighten limits on health-harming pollutants, including nitrogen oxides. The EU has said the health benefits would far outweigh the costs.
But countries, including the Czech Republic, oppose the proposed rules which they say are burdensome for industry. Most have big car-making sectors.
An EU official said the ministers had discussed the law's "unrealistic" deadlines and issues with equipment to enforce it.
"Our effort is, in the area of Euro 7, to make those conditions really realistic, to make them achievable," Czech Transport Minister Martin Kupka said following the meeting in Strasbourg, which he convened.
The Czech Republic said the countries had reservations on the short period for adoption of Euro 7, which under proposals should come into force in mid-2025 for cars.
It has proposed a four-year period for the regulation to take effect, along with some technical changes, to give industry time to prepare and boost technological measures.
"If we are really serious about trying to bring Europe to greater carbon neutrality, I think that really means bringing in technologically realistic measures," Kupka said.
The countries also discussed a separate row over the EU's 2035 deadline to phase out CO2 emitting cars, which would effectively make it impossible to sell new combustion engine cars after 2035.
Germany, backed by countries including Italy and the Czech Republic, wants clearer assurances that new cars with internal combustion engines can still be sold after 2035, if they run on CO2-neutral fuels, such as e-fuels.