In its development stage, C5 body panel distances, such as between the hood and the front fenders, were determined by putting a black prototype in GM's Climate testing center, heat soaking it to 140 degrees and determining how much panel expansion occurred -- primarily because of the fiber glass's heat expansion. (Highest recorded temperature on earth was 133 degrees in Death Valley.) It was determined that the minimum distance between most body panels needed to be a little more than 3/16" (5 mm to be exact). A generation later, this gap distance was re-tested and verified for all production C6's (something I witnessed as my C6 Z06 came to the very end of the production line, where I watched body panel inspectors run 5 mm blocks down each "hood to front fender" gaps, making appropriate adjustments).
Panel gap distance is majorly determined by the percentage of fiber glass (or glass fibers) in the Corvette's sheet moulded compound (SMC) body panels. C6 SMC panels are composed of 24.8% glass fibers. However, the percentage of glass fibers in the C7's panels has been reduced to 20.8%. Consequently, the panels swell in the heat less, and thus the C7 panel gaps have been able to be reduced from 5mm to 3mm (less than 1/8"), helping to improve the C7's appearance, and, surprisingly, slightly improve its aerodynamics.