European Union environment ministers said they would consider imposing binding restrictions on cars from South Korea and Japan if talks on airpollution standards were not wrapped up by the end of May. The ministers said they were concerned about slow progress in the talks, especially with the Korean car industry. The European Commission, the executive arm of the 15-member EU, has been attempting to convince Japanese and Korean manufacturers to make the same commitments to produce more fuel-efficient cars as their European rivals.