Give him a little time. He is still mourning the loss of his Mustang. Tell him if he doesn't want to give you the garage then he can build an addition to the house for you.
I worked a deal with my husband. He bought a Saleen, which is a Mustang on steriods, and wanted a garage for it. I told him the only way he could build a garage would be if he built me a sewing room. I got a great sewing room and he got a 3 car detached garage. Win Win.