A garage would get far too hot in the summer and the rabbit would be in the dark most times. Like you said, the garage door opening and closing would likely stress it out too. That's not a good life for a rabbit.
Indoors is a much better place. They can be easily litter trained, especially when fixed, they don't stink as long as they're cleaned up after (with the exception of an un-unneutered male, who may spray), and you can form a much better relationship with your rabbit when it's part of the family.
The best enclosure you can get is a dog pen. You can use a wire one like this,
View attachment 3102270
C&C grids
View attachment 3102272
Or these
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I recommend watching and showing your parents videos from Lennon the Bunny on YouTube. She has lots of useful information on everything including diet, bunny proofing, free roaming, litter training, and more. Once your parents are on board with keeping a rabbit indoors, I would consider fostering a rabbit to see what owning one is like. Of course, every rabbit will be different, but rescues will often provide and pay for everything you'll need while the rabbit is in your care (aside from fresh food usually).
If you have any more questions feel free to ask me