I saw a post about the HHO kit on one of the BMW forums - not sure if it was on this one, or one the 'fester or bimmer one. There was some initial interest - people were asking how it works, etc, then the thread died suddenly and nothing came out of it. probably didn't work as expected.

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Stable: e92is, e46 M54B25, e83 N52, e53 N62 - sold, e39 M54B30 R.I.P.