original_query: Which car manufacturers were involved in the discovery of software manipulating air pollution tests? What is the most relevant chunk to answer the query?
query: Which car manufacturers were involved in the emissions scandal involving software manipulating air pollution tests?
answer: Volkswagen, Fiat Chrysler, Opel (General Motors), and potentially others (like Nissan and Renault, though their involvement was investigated but not confirmed to the same extent as the others) were implicated in using defeat devices to manipulate emissions test results.