Throttle meaning pedal.or cruise control light pedal?Light pedal meaning constant speed? I would have hoped that M.B. has changed that too but i can hear rearend noise in alot of new cars.Depends how loud it is how i drive it wether the radio is on alot of things.Good luck ,But if it's the rearend let us know.I'll bet my 2cents it is.I have heard rear end noise in newer MBs and Jags etc.Oh that 30year old car was new when i heard it!And I was pissed then !And they made that model 23years!With different engines.Also since then I've always tried to remember to listen while I test drive any new car or old for rear end wine at constant speed.A friend of mine that imported MBs told me about it first and suggested turning up the radio.I told him that cheaper cars don't wine why does a MB.
ps. This is only a suggestion of what it might be.!!