I have tried the Rambler in game but not the Scout.
I travelled from Daymar to CRU L5 and hardly any fuel was used.
The Q&A on the site says this:
What advantages does the Cutter Rambler have over the base Cutter and Scout? - Purely from a numbers side, the Rambler has by far the biggest range, featuring more hydrogen and quantum fuel via additional fuel tanks. In addition to that, the Rambler has a much larger habitation area. This includes a large storage space for weapons, suit lockers, and a food processor to allow the player to stay out in the ‘verse for longer.
Hope this helps