...Yet at least twice, people risked a true interstellar journey in one, apparently believing that there'd be enough fuel for such a trip. In "The Galileo Seven", there were four star systems that the damaged shuttle could have reached, implying interstellar reach; in "Let That Be Your Last Battlefield", a desperate fugitive tried to escape from star to star in one.
Perhaps it's not recommended to do such long trips in a shuttle, exactly because there ain't enough fuel for the trip plus unpredictable detours. But it's still technologically possible. It might take weeks or months (even though in "The Galileo Seven" the nearest of the four system was apparently mere hours away), but eventually one would get there.
Timo Saloniemi