Instead of a roadable aircraft, how about using your aircraft to carry a roadable motorcycle? That question has been answered by the effort of MotoPOD, which debuted its modified 225-cc six-speed four-cycle motorcycle and aircraft belly pod at AirVenture Oshkosh last month. The company says it will soon offer STC'd models for Cirrus SR22, Cessna 182 and other aircraft models. For now, the system has been fitted to a four-seat Van's Aircraft RV-10 kitbuilt experimental aircraft for testing at a cost of 9 knots airspeed during cruise -- time the company says you can sometimes more than erase on the destination end of the trip by virtue of having brought your own ground transportation. As for other costs, first, a MotoPOD carrying one of the company's modified motorcycles (leak-proof plumbing and folding parts) will add more than 230 pounds to your aircraft. But before that, comes dollars.
A pod plus motorcycle will run you somewhere near $9000, give or take roughly $1000, less installation. The pod locks in place below the belly of the aircraft with a pin system, and a winch (which you can run externally with a handheld electric drill) lowers the pod to the ground where it can be wheeled out from under the aircraft on integral mostly recessed wheels. That installation means that the entire volume of the pod is accessible from its top opening. From there, the company claims it only takes minutes to make the bike road-ready and drive off.