The speed at which a car will lift off the ground depends on several factors, including the design of the car, its weight, and the aerodynamic properties of the vehicle. In general, for a conventional car without any special modifications or aerodynamic aids, the lift-off speed can range between 150 to 200 miles per hour (240 to 320 kilometers per hour).
However, it's important to note that cars are not designed to achieve lift-off during normal driving conditions. Lift-off typically occurs in extreme situations, such as during racing events, when the vehicle's aerodynamics and high speeds can generate sufficient lift to overcome the downward force of gravity.
If you're referring to a specific car or situation, providing more details would allow for a more accurate answer.