Our '90 300TE shows around 2750rpm at 100km/h (62mph) which by calculation is spot on for the 3.27 rear axle ratio.
For what it's worth, my 5-speed 190E 2.3 shows 2500rpm at 100km/h in 5th gear (0.8:1). My 350SLC runs at about 3000rpm at 100km/h.
Seems funny, the V8 has the shortest gearing, then the six, then the four. But then the four has the 5-speed whereas the V8 has the 3-speed auto.
107.023: 350SLC, 3-speed auto, icon gold, parchment MBtex (sold 2012 after 29 years ownership).
107.026: 500SLC, 4-speed auto, thistle green, green velour.
124.090: 300TE, 4-speed auto, arctic white, cream-beige MBtex.
201.028: 190E 2.3 Sportline, 5-speed manual, arctic white, blue leather.
201.028: 190E 2.3, 4-speed auto, blue-black, grey MBtex.
201.034: 190E 2.3-16, 5-speed manual, blue-black, black leather.