I also would say that putting the rabbit in a garage with cars would not be a good option, for the reasons others have already mentioned, however, I’d also say that putting a rabbit outside would be even worse (predators/extreme temperatures/isolation) as well as the problem of noticing health concerns early on such as GI stasis which can be fatal if not treated quickly.
I personally would do as much research as you can to show your parents why housing your bunny indoors is necessary. Such reasons include not subjecting your rabbit to loneliness, and the necessity of human company, among spotting health concerns fast, the danger of car fumes and noise in the garage, as well as ensuring that the rabbit is provided with sufficient space to exercise. Some would argue that if it was your parents who got you the rabbit in the first place, then it is their responsibility to ensure it has a good quality of life. Although, this could be seen as a harsh approach in which case, I’d also question WHY exactly your parents do not want the bunny in the house. Is it because they are not litter trained and causing a mess? Destroying things? Smell? All of which can be prevented, rabbits can easily be litter trained not to make a mess, rooms can be bunny proofed to prevent damage, and a well kept rabbit whose living space is kept clean does not smell. Try to understand their perspective and demonstrate how the ‘problems’ could be resolved.
