I noticed that one of my wheel caps had fallen apart. So here is a simple DIY on how to change your center cap.
Tools needed: 1. Knife
2. Center cap (Part# A 171 400 01 25 5337) for 2010 E550. (your center cap may vary)

Take your knife and pull off the center cap.

As you can see in the picture, the new center cap needs to be pressed in.

Align the center cap to the rim.

Press in until it's completely inserted.

Done!

Tools needed: 1. Knife
2. Center cap (Part# A 171 400 01 25 5337) for 2010 E550. (your center cap may vary)

Take your knife and pull off the center cap.

As you can see in the picture, the new center cap needs to be pressed in.

Align the center cap to the rim.

Press in until it's completely inserted.

Done!
