An answer to the horsepower and torque question is that you have to talk about horsepower at specific RPMs. The gas engine always gets it peak HP rating at very high RPMs. You will seldom rev the engine to this RPM and so you will seldom obtain the peak HP. A diesel engine on the other hand gets its peak HP at a much lower RPM and you will frequently operate at this RPM and obtain its peak HP. Another way of saying this is that you will frequently use the specified torque and HP of a diesel engine, and you will seldom use the specified torque and HP of a gas engine. You can also operate the diesel engine 24/7 at max output, but not a gas engine.
2014 Palazzo 33.2
Cummins 6.7 ISB, Allison 2100 6 Speed