There is much correspondence on the matter of the lack of a dipstick for the W210 electronic gearbox. My contact at MB (who I shall in future refer to as Herr X ) tells me that one reason is that if the dipstick is in place and the car driven there is a very high likelihood of the dipstick interfering with the operation of the 'box - and that would only cost a great deal of £££ to fix ! MB will not publicly 'fess up (as we say down here in south London) because they feel they might look silly in designing and then producing a gearbox that cannot cope with its own dipstick. The part number is: W140589152100. This tool is available from all dealers. I hope this helps.
I have followed the path of the DIY dipstick mentioned elsewhere.
I have followed the path of the DIY dipstick mentioned elsewhere.