Interesting analysis,
Interesting analysis, although the title is somewhat misleading: there are diesel hybrid vehicles, although not in the US.
I just wanted to point out something: if you disregard the torque advantage of the Diesel engines because " turbocharged gasoline cars are also torquey", you have to consider the fact that turbocharged gas engines, in general, use Premium gas. Right now the price of Diesel on my area is exactly 2 cents higher than the 93 octane gas, which for all practical purposes is negligible.
A Turbo Diesel Hybrid would probably be more advantageous in heavier cars, though.