itll depend on which model youre looking at because australia only adopted ISOFIX as a standard in 2013, so previous models wont have the "rear facing seats"
basically the aus govt read all the proof that ISOFIX seats reduced head and neck injuries in infants and totally ignored it until 2013 because it was too difficult to change the laws pertaining to the old "hook and latch" system we have used since 1989. not only did they ignore it, they made them illegal for use in australia, so any 2004+ model imported car that had ISOFIX or LATCH systems, had to have them removed to allow the car to be regestered (in case... gee, i dunno, in case the parents decided they wanted to use a safer child restraint system or something, heaven forbid)
annnyway, if by "we are trying to avoid purchasing a new car" you mean: we want to fit ISOFIX into our cruze, im sorry to tell you that they form part of the seat, and are not backwards compatable. so unless your seats have them, youre out of luck. youre pretty much stuck with the hook and latch system aussies are accustom to.
hope this has been helpful.