Here is my 2013 e350, still with only 38000 miles on it. Nothing really special. I bought it about a year and a half ago. the highlights:
1. Rims straightened/painted/decurbed (painted/decurbed by me, think I did a good job. Previous owner used wheels/tires for curb feelers.
2. White side markers (light up yellow, CANBUS LED)
3. Facelift-style Depo taillights for pre-facelift
4. CARPLAY box installed by me
5. Tinted windows
6. Custom aftermarket grille (note mesh installed), lightable star
7. Seatcover (driver) replaced by me, soon will replace passenger preventatively
8. MB winter mats
9. Wood trim 100% replaced with new MB wood trim (by me, it remains to be seen what I will get out of the class action lawsuit)
The tenth thing is actually fairly unique. I put in folding mirrors and modified the car’s firmware settings in order to use them. A new switch panel was installed (and then overlayed with brushed silver keytops). No US 2013 W212 had folding mirrors; they were not available as an option in the US. They fold when I lock the car and open when one of the front doors open.
I have a Quickjack with exenders and I do (most) of my own work as long as it's not too heavy.