In common terms, for a start, there's an initial amount of
resistance force, usually friction and air resistance acting on
your car, for example 1000N.
Your constant forward force, is let's say, 5000N, and is used to
drive the car, overcoming the friction, allowing you to have excess
force to increase your speed.
However, as friction increases with speed [Air resistance
largely], later your car will reach a limit speed point, where all
the force is later used to overcome the resistance whilst
maintaining your speed.
Of course if you start to look deeper into the situation,
factors such as momentum and inertia, it helps to give a clearer
view.