The biggest difference between a missile and a floating car is that the missile doesn't need to consider how to decelerate or land safely—but passengers do.
The floating car is capable of stable flight due to a delicate balance achieved by its size, weight, built-in floating engines, and power engines.
By using the floating engine to convert part of the floating car's own weight into forward thrust, perfectly balancing out the weight, a relatively stable acceleration is achieved, and this method also improves fuel efficiency. Without sudden acceleration or deceleration, takeoffs or landings, one can hardly see any flame jet from the back of a floating car.
