according to the news (a simple search will turn up all the newspapers reporting on it, so no need to link), German automakers tested their exhaust and emissions systems on humans (and monkeys) making them inhale nitrogen dioxide to see the results and effects of the exposure.

I guess the German scientists and automakers felt the tests with the Zyklon B 70 years ago weren't quite conclusive enough... no word yet on whether the test subjects were Jews..