If you’re not going to use grip on the road for propulsion you might as well make an airplane.
That's why fan cars can be considered cheating. The fan is made of mobile aerodynamic surfaces. The Brabham BT46B try to circumvent the rules by saying their fan was a cooling fan, it didn't work.
If you allow mobile aerodynamic surfaces, indeed, you are going to have aircraft. It is easy to imagine a car with actual wings, with flaps, ailerons and elevators.