John German is an American engineer who is the US co-lead of the International Council on Clean Transportation (ICCT).
In that role, his research helped uncover the Volkswagen emissions scandal of 2015.
[1] German was investigating what he thought[a] would be relatively clean diesel emissions in US cars, where standards are more strict than in Europe.
In light of the discovery and scandal, German recommends that other car manufacturers be investigated for installing potential defeat devices.
[1] German has a degree in physics from the University of Michigan, is married, and makes what The Guardian called a "modest salary" in his role at the ICCT.