My family owns both. The 35i power ratings are under reported by BMW. The 35d power delivery is inconsistent most days. If it is 50 degrees out I feel fast, If it is hot out, I feel slow. The 35d likes slow consistent changes in the accelerator pedal, the 35i does not care and just goes like a modern engine shoule.

Also, in the 3 series with the N55, switching to the 8 speed got them at least a half second increase for 0-60. Compare 2011 E90 N55 to 2012 F30 N55

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2009 35d, 2006 325i & 330i