German officials have been ramping up their enforcement of the diesel emissions regulations. Last week, German prosecutors fined Volkswagen one billion euros, for not supervising the employees who designed the testing software. The German government last year accused Audi of cheating on its emissions tests for high-end models. It was the first time it faced charges of this kind in its home country, according to Reuters. Audi was asked to recall about 24,000 A7 and A8 models that it produced between 2009 and 2013.