How many watts of electricity could this make, if it were removed from the car, and made to power an electric generator? Would there be any efficiencies compar

How many watts of electricity could this make, if it were removed from the car, and made to power an electric generator? Would there be any efficiencies compared to say, an ordinary gasoline piston engine with a camshaft, driving that generator? I'm guessing yes... which leads to the next question: Would a diesel motor (again, to drive a generator) be more effective than this one which uses gasoline? Why or why not?