a generic roll of trunk seal can be used here, The same ones used by classic car rebuilders. Usually they are of pretty decent quality.

The issue with most older model mercedes rubber even when bought new is that the rubber has already aged.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)