Sprawl and Postwar Growth

I just read the "Curbside Chat" booklet on the Strong Towns blog and found one observation that surprised me.  The booklet notes that after World War II, there was some public concern about the possibility of another Great Depression, "but another 'spatial fix' prevented that from happening... Only through the deployment of resources in bulding this new living arrangement was the United States able to sustain the demand needed to stabilize prices and grow the economy."   In other words, midcentury sprawl kept the economy afloat.

But Europe and Japan had far more balanced development patterns- and yet European and Japanese economies grew more rapidly than the United States.   For example, in 1950 American per capita GNP was about 7 percent higher than that of Switzerland, about 60 percent higher than that of the Netherlands or France, and five times that of Japan.  In 1973, after a quarter-century of sprawl, U.S. per capita GNP had fallen behind that of Switzerland, was only about 30 percent higher than that of France and the Netherlands, and was only about 50 percent higher than Japan.  Admittely, some of these countries were growing from a very low base due to World War II-induced devastation- but this was not true of Switzerland (which was not bombed or invaded during World War II).  

If the United States grew less rapidly than less automobile-oriented nations, what evidence is there for saying that sprawl was necessary for postwar growth?