Have no Fear.
Your E320 has a 4200rpm limiter . It only limits when in P/N. As soon as the speed sensor sees vehicle movement,
it is out of the circuit.
According to the data I have, the reasoning for this feature is to protect the torque converter from high rpm damage at stand=still.
For a test, drive the car 10 mph, shift to N and watch the tach with some gas. Should go right up to 6K with no problems.
It took me many moons to find this out , so there you gooooo....