The N55 did not appear in 3-series in the U.S. until the 2011 MY, so 2008 would definitely be the N54.
You didn't specify coupe or sedan but it this case it doesn't matter. Start of production for the N55 in sedans was September 2010. The coupes & cabrios continued with the N54. I think they were due to switch to the N55 also as of March 2011 production, but haven't double-checked that.
I wouldn't necessarily be concerned about the N54, but more about what your local dealer did to determine the car is "certified" and what that means to you. You can search the forums for some horror stories.
You might want to spend some quality time reviewing N54 issues at E90post.com or Bimmerfest.com to understand the full scope of N54 issues which include the HPFP, injectors, turbos, wastegates, ignition coils, sparkplugs, fuel pressure sensor, etc. It would also be informative to visit the NHTSA.gov website and review the reported safety defects on the 3-series with the N54 engine from 2007-2011.
E90 335i - High Pressure Fuel Pump failures, etc. E90 335i - High Pressure Fuel Pump failures, etc. Quote: Looking back at numerous prior posts, you will see a variety of positions expressed. Without a doubt, the 335 is Huge Fun to drive. Enormous bang for the buck, in the performance department. ... BUT ... Ownership comes at a cost. For some of us, that cost has been Very high and Very unpleasant. From my research, the majority of owners have not been afflicted with the cruel disease known as HPFP failure. But, many have encountered the failed gas tank pressurization pump. Many have and/or will get the opportunity to replace the entire cooling system, since it's made almost entirely of plastic.. etc, etc. Nothing new here. Are you a gambling man? Read below: . . . To be sure, many owners have not gone through these nightmares. That's what keeps us going on. The odds are actually with you. And, like I said at the beginning, driving one of these is simply a blast. You weigh the odds and assess your personal risk tolerance. Are you feeling lucky? .
BMW estimates that ~30% of x35i models produced from 2007-2010 will need the HPFP and possibly injectors/fuel pressure sensor replaced in addition to the approximately 25,000 HPFPs they have been replacing annually in the U.S. Their previous estimate to NHTSA.gov was 5%... so the 30% figure is probably low once again. The real issue is that BMW hasn't demonstrated that they know the root cause of the HPFP failures and each new HPFP part number they come up with (now at eight), has failed even after they assured BMW owners that the HPFPs from "943" onward was "the silver bullet" to cure the HPFP issues, which of course it has not. So this HPFP fiasco may continue on for years as the 2011 N55 powered models use the same HPFPs and they fail too. The safety issues can't be ignored as the NHTSA.gov safety defect complaints confirm accidents and many near accidents. http://www.insideline.com/bmw/bmw-recalls-150800-2007-10-vehicles-for-defective-fuel-pumps.html http://en.wikipedia.org/wiki/BMW_N54
