For a coupe, the S5's trunk is rather large, at 16.1 cubic feet. That compares to the BMW 3 Series' 11.1-cubic-foot trunk and the Infiniti G37's 7.4-cubic-foot cargo area. The S5's space is also rather functional; the backrests of the 60/40-split folding rear seat can be released from either the cabin or the trunk, and when folded they're nearly flat with the trunk floor. There's also a trunk pass-thru with a ski bag.