GM Design Chief Wayne Cherry is retiring later this year, and his parting gift to GM is the Sixteen luxury-sedan concept, which has under its gullwing hood the so-called XV16 concept V-16 engine, which displaces 13.6 liters and produces an equally incredible 1000 horsepower and 1000 lb-ft of torque. The Sixteen is an evocation of Cadillac's heritage writ large, with 24-inch tires, a super-luxurious cabin that seats four, an all-glass roof, invisible B-pillars, and extensive use of real crystal for both interior and exterior decor. It's rather unlikely that it will ever reach production, but Cadillac enjoys the advantage of actually having a V-16 engine in its past, even if it was 70 years ago, which gives the Sixteen concept a real sense of legitimacy.