Why does the Audi A4 make a rattling noise while accelerating?

I've noticed a rattling noise coming from my Audi A4 whenever I accelerate, especially at higher speeds. What could be causing this and how can I fix it?

The most likely cause of the rattling noise is a loose exhaust heat shield. It is a common issue in Audis and can be easily fixed by tightening the bolts or using exhaust system sealant.

Another possible cause is a failing catalytic converter. It can cause rattling noises due to internal damage. It is recommended to get it checked and replaced by a mechanic.