Well, also have to keep in mind that it's only a 3-cylinder. Smarts do tend to idle on the odd side in my experience. I guess you could say less like butter, more like oatmeal with a touch too much milk. Just a bit lumpy.Anyone's 453 run a bit rough at idle? I bought the car brand new and it wasn't this rough for the first 5k miles. I have tried different gas, etc asll the same. I took it to Mercedes of Sacramento and they said 2 things. 1 they have never even had a newer smart in there and 2 it was normal. If I rev it to like 1200 RPM's it is fine and smooth but just sitting at a light its definitely rumbling.
On another note, getting your 453 straight-piped only makes it more obvious. Lol
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