"Modular" vs. "Integrated"
Dual-purpose machines intended to fly and also to provide ground transporation come in two basic styles, namely "Modular" and "Integrated".
The "Modular" has two major components, the automobile, and the air frame. Whether you consider the combination to be a "flying automobile" or a "roadable aircraft" is a matter of emphasis, but the net result is that when the machine is used for ground transporation the two modules come apart. The airframe is either towed behind the car, or it is left at home or at the airport for use when needed.
Dual purpose machines that are self-contained, with all the components for flight and for driving included in the one unit, have come to be known as the "Integrated" vehicles. It may be necessary to extend or retract certain components when changing from one mode to the other. The big advantage that an "integrated" design has over a "modular" is the fact that all the components reside in the one vehicle. There is no airframe that has to be towed around, or stored somewhere. It is built into the machine. The conversion can be made from one mode to the other, preferably at the touch of a button.
But the "integrated" design pays a price for this convenience. All the gear and mechanical devices needed to protect, extend and retract the integrated airframe come at a cost measured in more than dollars. They add weight and complexity, as well as expense, to the design. Not only do they add to the expense for the builder, these devices also add operating expense for the owner. Over and above that, this convenience has limitations in usage. The operator of an "integrated" automobile / flying machine cannot just pull off to the side of the road, spread his wings and fly away. It is simply too dangerous, and it is also unlawful to do so! He too must travel to the airport to take to the air! This circumstance means that the expected advantage over the "modular" design is substantially diminished.
When all is said and done, there will probably be a market for both styles of "roadables". The size of these markets will most likely be influenced by anticipated vehicle use. The owner who will use his vehicle as a car, say 85% of the time, has little need of an aircraft incorporated into his personal ground transportation. This person will probably purchase a "modular". The individual who plans to use his dual-purpose machine mostly as an airplane, will probably favor an "integrated" design.