Most 1993 300e models in the USA had the 2.8 liter variant of the m104. Only a small minority were 3.2 that year. This car also has a 4 speed automatic, no overdrive, and no lockup torque converter. It's been a number of years since I sold mine so I don't recall exactly how fast the motor spun on the highway, but it was geared on the short side. I think about 2400 at 60mph is about right. Outside the city at Texas nominal it turned about 3k rpm. Mine never delivered great mpg, about 24-25 on road trips and 20ish around town.

Sounds like the OPs car is in third at 60. Possibly the Bowden cable that controls shift points is too tight, delaying the upshift to fourth. I think it's a simple tension adjustment at the throttle body, like other MBs of the era. This is an early drive by wire throttle though, so may be a bit different.