It's the killing ground where hundreds of thousands of dollars worth of SUVs, sports cars, and sedans meet their grisly end before they have more than a handful of miles on the clock. Some of General Motor's earliest work on building new models comes as much from tearing apart cars as it does piecing together fresh parts. That's the odd double approach of the Competitive Teardown Area, the high-security garage where cutting edge 3D printing and rapid prototyping sits alongside socket sets and angle grinders. The luckier cars start as homegrown constituent parts and leave as near-complete mockups of tomorrow's models; the unlucky ones - often wearing badges from Ford, Mercedes, Honda, Toyota, and other GM rivals - are making their final journey in one piece when they roll in through gates. It's the sort of place where, ordinarily, you'd need to be part of GM's engineering inner-circle to walk around, but SlashGear was invited to pay a special visit.