Originally Posted by TurboDan

This is the "Rumble Strip Noise" or RSN for short. Do a search on a Mercedes or Sprinter forum and you will see that this is very common. Some people have had luck with changing fluid, others not. The cause of the issue is the lockup torque converter clutch which makes noise as it applies (too early in my opinion), the trans controller also never fully applies the clutch so there is always slippage. Some newer Mercedes TCMs have modified code that helps to minimize the noise but I dont think it was ever made available for the Crossfire. My car makes the noise at about 40MPH and 25MPH with light throttle, 52K on original fluid.

-Dan-