Volkswagen's latest concept car will reach 60 mph in 6.2 seconds on its way to a top speed of 140 mph. With specs like that, most Americans would be surprised to learn that it also runs on diesel fuel and can return highway fuel economy of up to 50 miles per gallon. Developed for "maximum driving fun and minimal fuel consumption," the lightweight, 180-horsepower Concept BlueSport demonstrates how mean and green can be perfect partners. Combining the low-end torque of a 300-horsepower V6, a six-speed DSG transmission and 45:55 front:rear weight distribution, the compact, mid-engine, rear-drive roadster promises big fun. On the economy front, the BlueSport steals a couple tricks from the hybrid playbook, employing an automatic start-stop system and regenerative braking. In its quest to happily unite agility and frugality, it also foregoes a folding hardtop in favor of a lighter, manually operated cloth roof.