Dave - I believe it is in fact the "completion backwards principle." It is scientific fact that if you build it they will come!
My garage, 9 years in waiting, was restricted in size by the city because of the historic district we live in.
Side kick you garage and storage looks great, not to mention the car in progress that looks like a McClearan? My shop started as a wood shop and it was immediately too small for that. Add one ford truck and Harley , plus body parts, engine, tranny and storage stuff....and soon you will be tripping over stuff!
Then show it to your wife and filling it will be no problem!