I'm in your situation...I was on ebay looking at a 99 E430 being sold by a local dealer. Trying to decide it I want to take on another note, or just continue fixing the old W124.

If you are staring down a myriad of problems, understand that these cars are not collectibles. So investing time and money leaves you with a running vehicle, nothing else.

With a W210, you get to start fresh...

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car