One problem related to transmission not engage has been reported for the 1999 Mercedes Benz 320. The most recently reported issues are listed below.
Transmission disengaged then downshifted (1st) while driving. Brakes engaged. Car came to violent halt , then car and passengers were lurched back & forth uncontrollably without operator input, rpms erratic until key removed. Freeway incident would have resulted in fatalities. Car was not drivable, mfg denied similar claims, see NHTSA item # sb605899. Trauma of event has resulted in inability to drive vehicle (concern for safety and fear of reoccurance).