The US lowered tariffs on auto imports from the European Union to 15% retroactive to August 1, cementing the terms of the framework trade agreement the two sides struck this summer.

The Department of Commerce and Office of the US Trade Representative published a document online on Wednesday detailing the changes, reducing duties on a range of goods.

Shares of German carmakers Volkswagen, Porsche and Mercedes gained on the news. Porsche, which is among the hardest hit by the US tariffs as it sells only imports there, rose as much as 3.8 per cent in Frankfurt.

The changes include a list of exemptions for sectors including aircraft, aircraft parts and generic pharmaceutical drugs plus ingredients, as well as certain metals and ores, effective September 1.

Most of the new rates take effect for EU goods shipped starting September 1, but the relief for automobiles and parts was contingent on the EU introducing legislation to lower tariffs on American goods. The bloc followed through with that action on August 28, paving the way for the Trump administration to backdate the new auto charge.

Previously, those vehicles faced a 25 per cent US duty on top of existing levies.

The US said in its notice that the list of products may yet be amended. The move followed an executive order President Donald Trump signed earlier this month that smoothed the process for his administration to adjust tariff rates for imports from economies with which he struck trade pacts. --Bloomberg