I had the coil go bad on my 380sel. It was intermittent at first and then died on the road. I can't remember the exact details, but as I recall the problem lasted for awhile (at least weeks and maybe a few months) before the coil failed.

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07 E350 4Matic wagon, 06 S430 4Matic, 99 SLK 230
retired W210 (x3), W124, W126