Why is my Audi A5 making a loud rattling noise on the highway?

I recently purchased a used Audi A5 and noticed that when I'm driving on the highway, there is a loud rattling noise coming from the engine. It's not present at lower speeds or when idling. What could be the cause of this and how can I fix it?

The most likely cause of this issue is a loose heat shield on the exhaust system. This is a common problem in Audi A5s and can be fixed by tightening the bolts or replacing the shield. It's important to address this issue as soon as possible, as a loose heat shield can cause damage to other components in the engine.