Why does my Audi A6 make a knocking sound when I accelerate?

I recently purchased a used Audi A6 and noticed that whenever I accelerate, there is a distinct knocking sound coming from the engine. It is more pronounced when I am driving at higher speeds. What could be causing this and how can I fix it?

The knocking sound could be caused by several potential issues such as worn out bearings or piston slap, which usually requires a mechanic's attention. However, before taking it to a mechanic, check if your oil is at the proper level and quality, as low or dirty oil can also cause knocking noises.

Another possible reason for the knocking sound could be a damaged or faulty spark plug. It is best to have your spark plugs replaced every 30,000 miles or as recommended by your vehicle's manual. This can improve your engine's performance and prevent knocking noises.