The cost of fuel is a red herring. the lower cost of jets is in initial cost and cheaper parts. the cost for fuel is out of sight as most of them were older less efficient engines that could easily eat 4-800pph at ground idle (600pph =100usgallons/hr) and inflight numbers can dwarf this. Piston planes are like older computers, rarer and need more technical savy to use an maintain. Parts are not cheap, hard to find and people that know them well scarce. the upside is 75gph(imperial) of hard to find Green gas (130 octane) for a P51. Right now local prices for 100LL gas is $2.25! Allison