DÜSSELDORF, Germany — Volkswagen is taking the nautical-themed auto to the next level at Europe's largest recreational vehicle show with a concept car inspired by yachts featuring a wooden boat deck on the roof.The Caddy Topos Sail design concept is based on the Caddy, Volkswagen's smallest commercial vehicle, but hosts a wooden boat deck on the roof surrounded by aluminum rails. Panels on the boat-deck roof of the Topos Sail are capable of hinging upward to create lounger-like seating. Access to the roof comes from a ladder set into the rear hatch that picks up the same wood and aluminum nautical cues. Wood accents have also been placed in the rear bumper and along the side of the small van.What this means to you: Sunbathing on a boat: fun. Sunbathing on the roof of a car: strange. — Eric Tingwall, Correspondent