Oh well...win some loose some.
The PA32 300 I fly burns about 70ltr an hour. The Cessna 337 burns about 70 ltr an hour.
So i guess the cost offset come in to over all running cost. It costs more to maintain the 337 than it does the PA32. And I would guess it costs more to maintain a TB20 or C210 than it does a PA28 (Archer).
So all in all swings and round abouts.