China and Europe are two key global markets that are recording the largest slowdown, while the United States continues to try and hammer out new trade agreements. 

The auto market in China - where new-car sales fell 5.3% to 1.59 million in July - compared with the year-earlier period has also slowed due to worsening trade tensions.  For the full year, sales are forecast to grow 1.2% over last year, according to LMC Automotive, down from a 13% growth rate in 2016 and 2.1% in 2017.

At the same time, demand for American vehicles, which generally has acted as a universal global catalyst, has also topped out, largely due to higher prices and higher loan rates, but perhaps also due to rising nationalistic sentiment amid a "don't buy American" media wave.

Demand is also starting to wane in Europe, sliding to "prerecession" levels. Many American car companies had already struggled to maintain profitability in Europe where the slowdown in demand is exacerbating the bottom line.