I simply can't think of a scenario where a codes issue concerning dimensions for a garage could come into question except for specific requirements for parking requirements in urban or village settings, where so many spaces are require per bedroom or unit. But I have seen quite a few larger new homes where an unfinished, unheated room with a roll door exists that could not even fit a "Fit" but is added to house the owner's lawn tractor or ATV. How would codes come into play per the dimensions of such an area?It most certainly is an issue of Building Codes. Post a local Municipality as a test case.
We had a builder once, who became crazy (Schizophrenic) and eventually committed suicide. He built a shallow garage to try and reduce his taxes thinking they would arbitrarily assume the garage was 24' deep. The back of the garage was an oversized master bed. It worked for a while. The assessor caught on. I appraised the new construction after it was complete. He was asleep in the bed and didn't wake. His wife showed me around. His slide into the abyss was already showing. He stored the lawnmower there.play per the dimensions of such an area?

And then there's the ones that market "2 1/2 car garages".
I don't think this is an issue of public codes.
I agree with your comment. I believe the answer to your question however is one of functional utility and comparison to what exists within the immediate market. What are the dimensions of garages for your comparables? Are there any properties with cars of similar dimensions? What is the typical vehicle owned/utilized by residents of that market?My question was more about whether or not anyone uses a rule of thumb on size as to what constitutes a usable parking bay.
It most certainly is an issue of Building Codes. Post a local Municipality as a test case.