Originally Posted by mkoesel
N53 is the direct injected (HPI in BMW parlance) natuarlly aspirated I6. It starts shipping right about now I believe (March model changed) in the E93 and E93 330i, but only in countries with clean enough fuel (i.e not North America). In its first iteration it makes the same power as the highest output N52 (272hp), but with much greater fuel economy (I think 15% or so).
Interesting to know. Hopefully, the 2008 MY and on will take advantage of HPI.