The Isuzu engine is a touch 'under powered' in its specs compared to some because it is a very under stressed engine, thats why it has a class leading b10 rating.
People shouldn't get too caught up with specs, or killerwasps and such. At the end of the day we all have to sit on a 100 or 110kph so you can have all the power and fuel usage in the world its not going to offer you a hell of a lot in the real world. Yes its nice to have a ship load of grunt for that rare occasion you need to over take someone up a hill while towing but its few and far between.
Whats important in a diesel for towing in my opinion is a nice linear torque curve, and thats what the Isuzu engine has. It doesn't need a pile of killer wasps or 1000 bert newtons in torque, its power to weight ratio is actually quite good when you compare it to a 200 series cruiser for instance but its linear torque curve from idle is perfect for towing and off roading. And all at less than 9 ltrs per hundred I might add
I should be working for Isuzu Ute Australia