The fundamental problem of hovering is that you need to constantly exert an upward force on the car to stop it from falling. To exert a force without contact (i.e., no tyres touching the ground etc.) you need some physics that acts at a distance, such as magnetism, gravity, or radiation, or you need to shove a load of air downwards to get a reaction in the upwards direction. So, magnets would be one way of achieving the hovering without energy input, but you’d need magnets laid along everywhere you wanted to go as well. Trains in Japan work like that. Gravity would require a mass similar to that of the Earth but above the car – this isn’t really solving the problem so much as making it much much harder. Radiation would require a SHEDLOAD of energy to kick out enough to float a car. The shoving air downwards approach is how hovercraft and drones and helicopters work – but as you know they all require accelerating the air, and therefore require energy from something.