Average Fuel Usage for 38'ers

[Mate]

Please forgive my ignorance , I am a new member , and am extremely keen to learn as much as possible before purchase .
Im looking at a Cat in the 38ft range .
I have had some confusion with fuel burn amounts .
eg Lagoon claim to use 3lt/hr while Leopard owners are claiming closer to 7lt/hr.
Have I got this right , or are the lagoon threads Ive read possibly refering to per side .
Im not only looking at Lagoon or Leopard , but these are more recognized .
Does anyone know the fuel economy of a few known 38ft cats . I certainly dont want to disregard Leopard if I am simply confused. But that fuel usage would be considered to high for my liking, not that I intend to motor everywhere of course but still is a consideration with our much higher fuel prices here in Aus.
Hope you can help and look forward to hearing from you.
Regards , cheers Darren