Assuming the engine compartment is not too different from a standard 300E, it resides between the firewall and the intake manifold.
The filter resides top side up in a black plastic case. It is a bit smaller than a typical oil filter. I haven't removed mine yet, but some in this forum say it it easier to remove if you have the special MB wrench, while other say it's not needed.
If you do go about replacing it, use an OEM filter, not FRAM, or any other type.
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car