My 99 E300 has a resonance best described as a low pitched hum that comes and goes at 1 second intervals when driving between 60 and 65 mph.

The dealer says this is a known problem in 98-99 C and E classes and is related to the exhaust. They also say there is no fix.

My contention is that this is driveline related because it does not change when I change gears at the same road speed. It has done this since the car was new.

The service guy is going to call Mercedes on Monday but, in the meantime, can anyone offer any information? Thanks.

I have seen a faulty fuel damper hose cause this on the older D's... I have a '96 and it runs quiet and smooth. I would get this cured!
Also, be sure that the tires are a good brand (Michelin mxv4) and have the same amount of wear all of the way around.