Shares of Europe’s biggest automakers fell Wednesday, amid industry concern about the impact of the European Union’s new steel import quota plan.

European Automobile Manufacturers’ Association (ACEA), an industry lobby group, said the proposal goes too far and threatens automakers with higher input and administrative costs.

Germany’s BMW fell around 8% on Wednesday, slumping toward the bottom of the pan-European Stoxx 600 index.

The Munich-based carmaker, which is reportedly on track for its worst trading day since September last year, issued a fresh profit warning on Tuesday, citing slow growth in China and the ongoing impact of U.S. import tariffs.

Germany’s Mercedes-Benz Group, Porsche and Volkswagen were all down roughly 2%.

Shares of France’s Renault and Milan-listed Stellantis were last seen 2.5% lower and 0.3% lower, respectively.