The German Government has denounced experiments funded by German carmakers in which humans and monkeys reportedly inhaled diesel exhaust fumes.
Such tests could not be justified, the government said, demanding details. A minister called them "abominable".
Daimler also condemned them. VW is embroiled in a scandal over software that gave false diesel exhaust data.
In 2015 VW admitted having fitted "cheat" devices in the US that made their engines appear less polluting than they actually were.