How do you check the oil level manually on a 2003 Mercedes-Benz E320 model 211?

The manual only suggests one use the check oil feature in the instrument cluster electronic display menu - a manual method would be faster, more convenient and likely more reliable than this. A dipstick "stopper" is present in what would normally be the dipstick tube at the rear of the engine just forward of the firewall. What I can determine using a length of aircraft control cable suitably marked with the location of the full level in the sump, is that there is a sharp bend in the tube near the bottom that would preclude the insertion of a non-flexible rod/stick. As would be expected, the local dealer suggests one visit the shop periodically to have the level verified - good grief! YOU CAN BUY A WORKSHOP DIPSTICK FROM THE DEALER I think you are looking at the gearbox oil filler, the engine oil dipstick is normally front left not rear.