I’ve been thinking about The Centuries Unlimited’s flying cars.
Black Station split off from canonical history when a bunch of 22nd-century technology was dumped on it in 1929, so it has a Diesel-Punk aesthetic with gangsters and trenchcoats.
I considered plating the bottom of the cars in cavorite and putting a propeller on the back (top picture), but that just looks silly. I might use the design for the Steampunk aesthetic of Knickerbocker Station (maybe with the propeller in the front for a long nose?), but for diesel-punk I’m sticking with my original idea (bottom).
An engine pumps a suspension of exotic matter through a pair of coils, condensing energy into dark mater which fountains out of the center of the coil like exhaust from a rocket. The dark matter particles don’t interact with normal matter, but they have mass, which means shooting them in one direction produces opposing thrust.
One thrust coil is oriented along the car’s Y-axis, and swings back and forth to steer the car (controlled by a yoke). The other is much larger, oriented along the car’s Z-axis, and provides lift and (when rocked backward or forward), forward or backward thrust. It’s controlled by pedals).
The result is something that looks like a gangster car and even controls like one. I will have to make some changes, though, to the way you pilot it. There are two engines you have to ignite: the pumps for the levitator coil and the steering coil. Instead of changing gears, there’s a series of knobs you have to turn to adjust the speed of fluid through the coils. When you go up, you don’t point the nose of the car forward like a plane, you crank up the RPMs in the levitator coil and rise like a balloon. Going forward at great speed, the nose of the car will dip. Steering works like a car (the nose slides sideways) rather than a plane (which can bank). There will be very little friction, so breaking requires thrust (tipping the nose up).
Driving one of these things will probably feel like piloting a motorboat. In three dimensions. On ice. Sound properly greasy and horrifying?