One problem related to engine rattling and whining sounds has been reported for the 2015 Audi A8. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2015 Audi A8 based on all problems reported for the 2015 A8.
The car experienced a oil separator failure. The made an extremely loud whistling sound at idle. This is a known issue and Audi issued a TSB for it but did not issue a recall. The car ran very rough. To fis this issue I had to pay over $2,000 to have an new version of the oil separator installed. Audi should issue a recall on this since they know the original part is defective.