According to Jalopnik, the C6W is inspired by a 1976 race car with two sets of front wheels, designed to reduce drag and "increase air penetration." But those don't really factor into the C6W's design--instead, the extra two wheels provide better braking, grip, and absorption of frontal impact, and reduce risk of aquaplaning and deflated tires. They also greatly increase the amount and magnitude of head-turning, but that's not really a benefit that can be precisely measured.