Hello! ima guy from Norway who wanna buy a 2002-2004 SVT lightning (the 5.4 v8 compressor)

i was trying a lightning from a guy who was trying to sell it and he said he could drive it on about 12 liters on 100 km of nice driving. i really dont think so, thats why im asking here. the price on gas here in Norway is about 2,2 USD per liter so its very expencive.

Thanks!