Three words: "Barriers to entry."<p>Competitively manufacturing a car became a more and more expensive thing as volume sales allowed steadily more serious tools and tooling to be applied to the problem.  Per unit design also became cheaper as volume rose.<p>As far as I can tell the barriers to entry in much/most/all but x86 processors??? of what Silicon Valley does are steadily dropping and look to continue.  The process of design also looks like it's getting better/faster/cheaper for a whole bunch of reasons, and I doubt that happened in a big way in the auto industry until CAD was adopted, by which point Chrysler had probably bought AMC, finishing US car industry consolidation.<p>Consolidation is fine for an industry as long as it doesn't stop new companies from forming and becoming successful.<p>And, hmmm, a note on the Big-3: how many of their competitors failed to exit the singularity of WWII?  All got converted to wartime production, did some not bother to go back to cars and/or civilian trucks?