Shares of Europe's biggest carmakers traded lower Wednesday, amid concern that the European Union's latest efforts to protect the domestic steel market could threaten the region's auto sector. The European Commission, the EU's executive arm, announced Tuesday that it plans to hike steel tariffs and sharply cut import quotas, seeking to offer "strong and permanent protection" to the region's steel industry. The proposal includes a push to limit tariff-free import volumes to 18.3 million tons a