Diesel fuel has a higher BTU content than gasoline.
The combustion event in diesel engines last 30-40 -60 degrees ATDC .
Key to thermal efficiency they have.
The torque they produce can only be partial matched by Gas engines with High Psi Boost.
Of course you must feed huge amounts of gasoline in with High Octane to prevent detonation.
Diesel engines do not have detonation issues typical.
Nitromethane is still most powerful.
Short lived engines for all out race like Top Fuel.
I do have a Duramax and it is a pretty decent engine.
We also have a diesel in my wife's Equinox . It is a turbo'ed 4 cyl and we average around 38/40 mpg combined. The best mileage so far on the highway has been 50.6 mpg's. I keep searching for the sweet spot, I think it is around 61/62 mph, which I am good with when we are pulling 50+ mpg's. Once I get the rpm/mph completely figured out, then when we go on trips it is really inexpensive. Even the Cruze we used to have couldn't come close.
The Duramax is an LLY, it was one of the overheaters. I did some changes and added an additional radiator behind the bumper and fixed it. The only thing I am watching now is that I don't blow a head gasket. I maintain the truck religiously. It is an 04.5, only has 90K miles on it and is completely rust free, even though I live in NE Ohio.
I saw an 05 Duramax that was traded in with 750,000 on it. The guy hauled travel trailers to dealers from the manufacturers.