I still see the rubber straps on the city buses around my area, but that may be the city being extra cautious due to the buses being CNG fueled.


As to the grounding straps as it relates to MB's, I'm not sure about the other models, but on my w126, there are little spring loaded clips stuck into the spindles that rub on the oil cap.
The explanation that I was given for those little clips was to help ground the car through the tires, making a more reliable circuit than trying to conduct through the bearings.

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-Josh
Testing the cheap Mercedes axiom, one bolt at a time...