assuming this "car" has wheels and tires then it must have some pressure or "weight" on the tires to maintain control. so "weightless" is really not an option. if you would like a light weight car that can travel in three axis, I would suggest a car with a fan that would cause a suction force to hold the car to whatever surface it is on. As long as the suction is greater than the weight of the car itself you should maintain control even upside down.
Mark

I have seen something similar on a Harry Potter movie,the car was weightless and could move on all three axis !