Most Emission-Efficient Ro-Ro Cargos
Ships ranked by AER (Annual Efficiency Ratio) — grams of CO₂ emitted per tonne of deadweight carried one nautical mile (g CO₂/dwt·nm), the IMO carbon-intensity metric behind the CII rating — from official EU MRV emissions data for reporting year 2025. Lower is greener. Pick a segment and size class to see the greenest vessels first.
| # | Vessel | Size (DWT) | Built | Carbon intensity — AER (g CO₂/dwt·nm) | Grade |
|---|---|---|---|---|---|
| 201 |
MYKINES
IMO 9121998
|
6,047 | 1996 |
48.8
|
E |
| 202 |
SIGRID
IMO 9631840
|
2,530 | 2013 |
49.4
|
E |
| 203 |
AUTOSKY
IMO 9206774
|
6,670 | 2000 |
50.1
|
E |
| 204 |
AUTOPRESTIGE
IMO 9190157
|
4,311 | 1999 |
50.5
|
E |
| 205 |
EOS
IMO 9132014
|
8,936 | 1998 |
51.6
|
E |
| 206 |
VILLE DE BORDEAUX
IMO 9270842
|
5,291 | 2004 |
52.8
|
E |
| 207 |
ARK DANIA
IMO 9609964
|
6,551 | 2014 |
52.9
|
E |
| 208 |
ARK GERMANIA
IMO 9609952
|
6,551 | 2014 |
53.5
|
E |
| 209 |
CAESAREA TRADER
IMO 9117985
|
5,215 | 1996 |
54.8
|
E |
| 210 |
NEPTUNE DYNAMIS
IMO 9240976
|
5,600 | 2002 |
55.5
|
E |
| 211 |
VILLA DE TAZACORTE
IMO 9399325
|
10,140 | 2010 |
56.7
|
E |
| 212 |
NEPTUNE AEGLI
IMO 9240964
|
5,600 | 2002 |
56.9
|
E |
| 213 |
POWER
IMO 9506215
|
5,600 | 2012 |
57.2
|
E |
| 214 |
CITY OF HAMBURG
IMO 9383558
|
3,500 | 2008 |
59.5
|
E |
| 215 |
PRECISION
IMO 9506239
|
5,600 | 2012 |
60.6
|
E |
| 216 |
BOUZAS
IMO 9249996
|
4,695 | 2002 |
60.6
|
E |
| 217 |
CIUDAD DE CADIZ
IMO 9383560
|
3,500 | 2009 |
62.0
|
E |
| 218 |
PROGRESS
IMO 9506203
|
5,600 | 2011 |
64.5
|
E |
| 219 |
BLUE CARRIER 1
IMO 9186649
|
4,650 | 2000 |
64.6
|
E |
| 220 |
NIVIN
IMO 8206533
|
1,626 | 1983 |
65.9
|
E |
Which engines power the greenest fleets?
The main engine is the single largest CO₂ source on board — typically well over 80% of a ship's emissions come from propulsion. We aggregated this ranking the other way around: every engine design is scored by the measured carbon intensity of the vessels carrying it, licensee-built units merged under their design brand. The verdict from the 2025 data — modern dual-fuel designs like MAN B&W's ME-GI and WinGD's X-DF families, together with EGR/SCR-abated and ultra-long-stroke G-type engines, consistently power the most emission-friendly ships in service.
AER (Annual Efficiency Ratio) = annual CO₂ emissions ÷ (deadweight × distance sailed), the IMO carbon-intensity metric used for CII ratings. It is built only from measured CO₂, distance and deadweight — not the self-reported cargo transport-work figure, which is unreliable. Implausible outliers (top 2% per segment) are excluded. Grade A–E reflects each vessel's rank within its segment. Source: EMSA THETIS-MRV.