None of the MB's we've owned were very good "creepers." Our Subaru and Mazda both move around easily with the service brake off and idling. Even up a driveway. Not the Mercedes'.
It takes some time to get used to the different pedal travel. On the W202, W210, and later cars, the gas pedal has less travel and is a little lighter, but still very different from any Japanese car. Is the idle proper? Should be 600-700rpm in gear.
Go drive an older Porsche 911. The pedals are bottom hinged and come out of slots on the floor. That sure takes some time to get used to! You "Stomp" them...
1998 C230 "Black Betty"