Don't need to. That loss is a given on BOTH VERSIONS of the Piston engine.
But then you have ADDITIONAL LOSS on the Direct Drive Piston engine because
1) the drive train is less efficient
2) it is usually operating outside of its ideal band.
So your Direct Drive Piston motor is running at more like 10%-15% of fuel efficiency vs. the Gen set.
Meanwhile the Cruz first has to run down its battery (35 miles - ie roughly 1 gallon of gasoline) before the gasoline generator kicks in. And remember this was charged from a centralized powerplant running at 70% fuel efficiency.
Yes there are line losses. But these are about 5%
http://www02.abb.com/global/seitp/seitp202.nsf/c71c66c1f02e6575c125711f004660e6/64cee3203250d1b7c12572c8003b2b48/$FILE/Energy+efficiency+in+the+power+grid.pdf So we are still running at 65% efficiency on the first 35 miles, vs. 15% efficiency for the Direct Drive vehicle.
Now on a standard car the 1 tank range is roughly 300 miles. To make numbers easier lets assume that its 10 gallons (that's above current CAFE Standards but below the most fuel effective cars). And that is run at an efficiency of say 12%.
Meanwhile the Cruze runs at 65% efficiency for 35 miles, and then because of how the drive train is structured, it runs just like the Direct Drive Piston engine EXCEPT that we get to recover REgenerative braking energy. So that would put as at say 15%? So that's 265 miles at 15%.
Right off the bat we are well ahead with the Cruze. And that's with the Cruze operating the Gas engine in the LEAST EFFICIENT mode. IF OTOH it operates as a generator for the batteries, it is running in its optimal powerband. So that puts us up to at least 20% efficiency...
Sorry, the hybrid is more efficient.