Concern that the fabric on the seats could catch fire has prompted Toyota to stop selling six popular models of its cars and trucks in North America. It says the problem is that some of the soft material underneath seat covers in cars and trucks equipped with seat heaters doesn’t meet flammability standards. It’s telling dealers to stop selling 2013 and 2014 Camrys, Avalons, Sienna minivans and Tacoma trucks as well as 2014 Corollas and Tundras. Vehicles already on the road may be recalled.