The Jeep Wrangler in driveways today isn't inspired by a WWII military vehicle -- it's the same design lineage, unbroken, from a 1940 Army contract. The Humvee's civilian spinoff has an even stranger origin story. Both are proof of the same underlying reason the US government has never let its civilian auto industry go: it's the tooling, workforce, and supply chain that lets the country retool for war in months instead of years.