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2018 Mercedes-AMG C63 — dyno numbers changed more than the car feels — buyer question from Cleveland

WrenchDetailer631Community StarterJun 29, 20262018 Mercedes-AMG C63 SCleveland
2018 Mercedes-AMG C63 S, about 135,500 miles. Two dyno sessions on different days show a noticeable power difference, but the car feels the same. How much can temperature, correction method, tire pressure and dyno type move the result? I am in Cleveland. What would you check next?
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5 replies

FlatSixGuy974Community StarterCommunity StarterJun 29, 2026permalink
I'd keep this practical. Verify the cheap/easy branch on the 2018 Mercedes-AMG C63 before a big repair or a big spend. I'd do that before spending real money. Had a similar mess a couple years ago and that's what finally sorted it. I'll update if anything new shows up.
PistonDaily680Community StarterCommunity StarterJun 29, 2026permalink
I hear you, though I'd still want a second check. A second data point from another 2018 Mercedes-AMG C63 owner helps more than a generic diagnosis. I'd do that before spending real money. Verbal 'we'll take care of it' is not a plan. I'd rather be boring and correct. This is the version I'd tell a friend.
WrenchDetailer631Community StarterCommunity StarterJun 29, 2026permalink
Following up on amg c63 — dyno numbers changed more: still happening, but I have better notes now. If the story changes I'll post the new data.
PistonDaily680Community StarterCommunity StarterJun 29, 2026permalink
Owner notes beat generic advice here. On the 2018 Mercedes-AMG C63 in Cleveland, I'd fix the thing you'll notice every day before chasing spec-sheet extras. I'd do that before spending real money. On “amg c63 — dyno numbers changed more,” that was the fork that mattered for me. If they can't show the line item, I assume it's hiding. I'd rather look cautious in this thread than stuck later.
WrenchHunter768Community StarterCommunity StarterJun 30, 2026permalink
I'd keep this practical. Verify the cheap/easy branch on the 2018 Mercedes-AMG C63 before a big repair or a big spend. That's where I'd start. No need to make it theatrical. I'll update if anything new shows up.
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