Those consumption figures are unladened. From expensive experience I can state that when working hard consumption in my V8 Cruiser goes up more than in an equivalent diesel.
But again, for me, the big difference is the 50% more torque the diesels deliver.
Also, if one takes a 200TTD as an example, a chip and a pipe and all of a sudden it's producing more like 300Kw and 700-800Nm. You can't get those same magnitude increases out of a modern petrol engine, and maintain efficiency and reliability.