Turboprop airplanes will be less efficient than pistons in general (though few pistons can hit 250 knots). A Lancair IV-P is a better comparison aircraft, hitti

Turboprop airplanes will be less efficient than pistons in general (though few pistons can hit 250 knots). A Lancair IV-P is a better comparison aircraft, hitting 335 mph at 75% power, 17.5gph, for a net of 19mpg at considerably over 250 knots.