The skycar was invented on Earth by Paul Moller. It's a form of small aeryodyne – an aircraft in which lift and maneuvering are primarily controlled using vectored thrust rather than moveable control surfaces. Thanks to their sophisticated control electronics, skycars are as easy to use, and as safe, as automobiles.
The typical skycar is propelled by four enclosed fan-pods which can be pivoted between vertical and horizontal positions. In vertical mode they allow the skycar to take off and land like a helicopter, while in horizontal mode they provide faster and more efficient travel. The fuselage and canopy of a skycar is designed to serve as a lifting body, and most skycars also have stubby wings.
Most skycars are computer-controlled, meaning the pilot enters a destination and the computer plots the course and flies the aircraft. There are controls to allow semi-manual flying of the craft, but using manual control is strongly discouraged in populated areas, because of the hazard to traffic control. You can get a ticket if you take the controls and it's not a real emergency. In the wilderness of our frontier planets, the use of manual control is much more common.
Skycars are typically designed with two motors per fan-pod (eight total!), so if one fails the vehicle can still fly and make a safe emergency landing. Also, they are commonly equipped with an emergency parachute that can deploy to lower the entire vehicle safely to the ground.
The requirements of a landing site are basically the same as those of a helicopter. Most landing pads will have an electronic wind sock which transmits data to the skycar's computer for a smooth touchdown, and a nearby hanger (or garage, if you prefer) where the skycar can be kept out of the elements. Although skycars can taxi on the ground, they aren't usually considered a proper substitute for an automobile.
The capacity of skycars varies much in the same way that automobiles vary – there are two-seaters, four-seaters, and larger skycars which are the equivalents of vans or SUVs, not to mention ambulances.
Skycars on different worlds have very different power sources and methods of operation. Skycars on Luna and Mars, with their low gravity and enclosed habitats, are always propelled by electric motors in their fan-pods, and use rechargeable supercapacitor power cells for energy storage. Actually skycars are of very little use on Mars, due to the tunnel systems, and have only limited use in the underground dome habitats of Luna – as prestige limousines for the elite, or as ambulances or law enforcement vehicles.
Skycars on Oceania and Annyrion operate under higher gravity and have much higher range requirements. As a result, most of them are designed as hybrids with turbine or rotapower engines driving a generator, which in turn powers the fans. Some of the smaller, consumer-oriented cars have a power cell which can drive the fans during takeoff and landing, in order to keep engine noise under control. Some of the larger skycars used by the military, rescue services, or for development in wilderness areas are powered only by rotapower engines mounted directly in the fan-pods. These are quite noisy when lifting off or landing. The fuel is most often a form of biofuel (such as biodiesel) derived from cultivated algae.
Skycars remain more expensive than automobiles, and are usually available only for the well-to-do or for institutions and large corporations.