Hello MBWorld
I would like to take the time, to thank you for allowing us to get access to all this useful feedback. Unfortunately I have been dealing with some mechanical issues myself.
I have a 2003 Mercedes E500 with 175k miles, I has a rough start, but runs. When I put it in gear it moves as desired. After running for 10 minutes, it's the opposite. Shifts perfect but wont move when gas pedal is being pressed. Similar as it was on neutral but its really in gear like D or R as per say. Rpm's move forward when pressed on the gas pedal but the vehicle doesn't! Any in sight on this issue. I'm sure this isn't un heard of any fed back would be highly appreciated. Thank you everyone in advance. Hope we finally get the solution for us Mercedes owner's

Check fluid level.

Thank you MBWorld.
For giving me a fast response, & a probable cause why my e500 won't move when in gear. I will most definitely check my transmission oil first thing in the morning. I believe it's a black cap with a red lock clip that holds the cap in? I will also need a long transmission dip stick? If transmission fluid turns to be at an ok oil level, then what else could be the cause of of my vehicle not being capable of moving forward or reverse when put in gear?

You'll have to get or make a dipstick tool for that car. There are tutorials how to make that tool. You have the correct dipstick hole.

Check and see if you've got any fluid in the cable bundle going to the lower right hand front corner of the transmission. If yes, there could be a problem with fluid in your transmission control module.