A Gulfstream G700 carries 22,407kg of fuel (about 6,100 gallons at 800kg/m^3 ) and a max range of 14,353km (8,918.5mi), for 1.45mpg. Closer to 10x, by a bit. Using the 12,316km high-speed cruise range manages to bring it down to 1.24mpg, just under 10x worse.