I have a 2010 GL350 and in the trunk, where the AdBlue tank is, it looks like something is missing. Just to the right of the Adblue circular cover is a big, empty space...it looks like something belongs there. It looks like a big space in the shape of a 3D letter I . Does something belong there like a tire air pump? Please check your 320's and 350's and report back. Thanks.

 

Nothing came in that spot in my 2009 GL320. I use the empty spots to hold useful tools and supplies, like tire plugging kit, CO2 inflator, bottle of oil, jumper cables, air pressure gauge, etc.

 

Do you have the wheel chock?