Why does my Audi A5 make a loud rattling sound when I start the engine?

I recently noticed that when I start my Audi A5, it makes a loud rattling sound for a few seconds before quieting down. It's especially noticeable when the car has been sitting for a few hours. Is this a cause for concern?

The rattling sound you are hearing is most likely due to a failing timing chain tensioner. This is a common issue in Audi A5 models, and it's important to get it fixed as soon as possible to avoid further damage.