Dutch vehicle designer Allert Jacobs knew that his fuel-sipping, shell-encased motorcycle was street-legal. Unfortunately, the police didn’t, and impounded it after pulling him over during a test run.

But Jacobs has a lot of patience. He first built a resistance-reducing nose cone in 2007, in an attempt to increase his Honda Innova 125i’s 114-mpg rating. That design fell short, so he built a 1:5 scale model, followed by a full-size polyurethane and wood mold. By 2009, he was crafting the fiberglass shell. Steel tubes welded to the bike’s frame attach it, and a frame and rails added to the front of the bike allow the front of the shell to slide forward like a door and lock shut. Last winter, he even made aerodynamic cones with indicator lights for his side-view mirrors.