Halo Interceptor Multi-Functional Vehicle w/Attachments

The Halo Intersceptor is a concept vehicular hub, which begins as a sports car. With attachments, the Halo can be converted to a helicopter, a catamaran speedboat, or a jet aircraft. Conceivably a submarine attachment could be designed as easily as the cat speedboat or jet flyer.

Each attachment must be carefully maintained and stored until needed. Of course the attachments could be stored in different locations of maximum anticipated need. Attachments could even be shipped by boat or rail to the next location of use -- or you could have multiple attachments ready at several locations if you have the budget for it.
H/T Brian Wang

Al Fin operatives prefer a single vehicle which is self-modifiable without attachments, to serve multiple functions. But it is easy to imagine larger organisations such as the US military incorporating a HumVee hubbed multi-functional vehicle that can act as either helicopter or hovercraft, besides its basic land function.