Fleet Carbon Intensity by Engine Design

How this ranking works: every EU-MRV-reporting vessel is scored by its carbon intensity (AER, g CO2 per dwt-nautical-mile) relative to other ships of its type — so tanker engines aren't compared against container-ship engines. An engine model's fleet score is the average efficiency percentile of the vessels carrying it (0% = greenest fleet). Median AER is the absolute intensity. This is a fleet association, not a certified engine-efficiency rating or regulatory CII grade. Hull size, age, speed, fuel and operating patterns also affect results. Each vessel counts once per design. Only installations explicitly recorded as main engines, without a conflicting catalogue role, with at least 5 MRV-reporting vessels are ranked. Most large two-strokes are built under license — class registers record the licensee (Hyundai, Mitsui, Doosan, …), so identical designs are merged under their design brand (MAN B&W, WinGD, Wärtsilä, …) with the actual builders listed underneath. D/E fleet counts vessels on the design currently at CII band D or E; top retrofit is the most common eligible engine-family measure across the reporting sample, not only its D/E vessels. Retrofit eligibility depends on class equipment records, which do not cover every vessel equally — treat these two columns as indicative, not exhaustive.