Litter box in garage such a good idea! One commenter noted a potential problem with the car exhaust in the garage and the cat door--whether it would be sufficient to keep it out. But we had a cat door in our old house to the garage and never had an issue.
Now THIS is a cat tree! The Catframe combines a contemporary wood cat tree, sisal rope scratching posts, cubby holes, soft pads for kneading and sleeping, and last but certainly not least – storage for all kitties toys and treats.