Question: what is the most fuel efficient marine diesel engine?
Answer: Caterpillar C8. ... , Caterpillar C12.9 Marine Diesel Engine., Caterpillar C18 Marine Diesel Engine., Caterpillar C32 Marine Diesel Engine., Cummins QSB 6.7 Marine Diesel Engine., Cummins QSC 8.3 Marine Diesel Engine., Cummins QSL 9 Marine Diesel Engine.