A lot of the plastics that carmakers are using cannot be recycled.汽车制造商使用的许多塑料制品是无法回收利用的。American carmakers face stiff competition from Japan.美国的汽车制造商们面临着日本对手的激烈竞争。Investors are plagued by doubts about Detroit's Big Three carmakers.投资者对底特律三大汽车制造商一直心存疑虑。