I have a 4LHA-HTP160 (turbo) in my single engine 24,000 pound trawler with the ZF Marine 63A 2.5 reduction transmission.
95% of my 713 hours of cruising since new has been at 2,000 RPM. Fuel usage calculated by gallons replaced to full tanks.
Fuel burned - 1,252.7 gallons in 713 hours = 1.76 GPH**
5% of cruising at 2,600 RPM (Max torque) to reduce effects of under-loading.
** Includes fuel used to run Northern Lights 5KW gen-set for 230 hours and Hurricane 25,000 BTU heater for 360 hours.
Hope this is helpful.