Polymer chemistry & polymer technology have reasonably progressed so as the finished products, that come out of them, can be trusted. It is true that polyuerthanes (PU) are made by the reaction of the "harmful" diisocyanates & diols but once the reactions are done properly with correct molar ratios, the hazardous effects will be neutralized & the final products are safe to use.
We live at a time in which nearly 1/10 of the weight of a typical car is due to plastics. About 15% of these plastics are PU. It is in the best interests of human beings to increase the amount of plastics in cars as well as other means of transportation but this is a lengthy subject to go over .
I do not deny that a "bad" human & environmental impact will occur when a car is burnt but the benefits of plastics surely outweigh these relatively "rare" incidents.
Attached is a fact sheet about the benefits of PU in means of transportation.