Why does my Audi's engine make a rattling noise when I accelerate?

I've noticed that my Audi makes a rattling noise when I accelerate, but it goes away when I reach a steady speed. What could be causing this and how can I fix it?

The rattling noise could be caused by a loose heat shield on the exhaust system. It's a common issue with Audis, but not a major problem. It can be easily fixed by tightening the heat shield or replacing it if necessary.

Another potential cause of the rattling noise could be a faulty tensioner or pulley in the engine drive belt system. This can cause the belt to vibrate and create the noise. It's important to fix this issue as soon as possible to avoid further damage to the engine.