One flaw in the car hypothesis is that the car seat to roof distance declined significantly from about the 1920s to the 1950s. Early motorcars had enough headro

One flaw in the car hypothesis is that the car seat to roof distance declined significantly from about the 1920s to the 1950s. Early motorcars had enough headroom for their gentlemen owners to wear their tophats. The change was partly motivated by increased emphasis on streamlining, but if hats were still important, room would still have been provided for them. I suspect WWII had something to do with it, but I can't figure out how. Certainly pre-war cars had much higher roof-lines than post-war cars.