I have recently purchased a 98 E320 and this is my first MB so I might be wrong is asking this question.

I have been a passenger aboard many MB's and have always found them to be very smooth,but I seem to have a symptom that that I can only discribe as a " harmonic vibration". At just about any speed above 45, as long as the engine remains in a constant state of power I get what feels like a pulsing type feeling throughout the car and what sounds variable in pitch.

I want to say that I have been through this car and it was a CPO by the previous owner and now myself (3rd owner) I have no pulling left or right,no brake pulsation, nitrogeon filled tires at less than 3000 miles old,and NO vibration in the steering system at all.

Car has 150k and honestly in perfect condition,other than the radio issue (volume) and this, so I would like to figure out what this is and if I can fix it.

It is not particularly loud or noticable but I can feel it .

Thanks for any input.