Here is the (unbelievable) reply from Audiusa:
"I am following up as promised in regard to your question about a trailer hitch for your 2015 Audi Q3. I contacted Andre in the Parts Department at YBH Audi. He confirmed that the trailer hitch is not an available accessory for your vehicle. The 2015 Audi Q3 is equipped with a 4-cylinder engine, and does not have enough power to support towing. As this is a safety concern, we cannot provide a recommendation on an aftermarket part that can be used.
While this is not the information you were looking for, I hope if provides some clarification. Should you have any additional questions, please do not hesitate to contact me directly at +1 877 615 2834 (extension 43215). If I am unavailable, please provide your reference number listed above and one of my colleagues will be able to assist you. We are available 24 hours a day, seven days a week to assist you.
Just so you are aware, you may receive a survey via email within the next couple of days. The survey is in regard to the level of service I provided. I would greatly appreciate it if you have a few minutes to complete the survey to share your valued comments with us.
Warm Regards,"
Come on! Not only is the hitch reciever needed for the bike rack accessory, it is available in the ROW for 4 cylinder Q3's. What a ridiculous answer! Oh, and the owners manual talks about towing...