Wrong. Thirty-five years ago you could still find a physicist talking about a cetrifugal force. But that force doesn't exist; it only appears to exist; it is a fictitious force. A gravity field does not emerge to push you into your seat. The gravitational field is there all along. And since it doesn't accelerate you at all, the force of gravity is in equilibrium, and therefore the net gravitational force is zero.
What you feel as a mysterious appearance of a gravity force is only a contact force of the seat of your car pushing against your body. Since your body is not accelerating in either the horizontal or vertical directions, your body pushes back with a contact force. What you feel is that interplay between contact forces, and what eventually accelerates you forward is the friction forces between your body and the seat, not a mysteriously created gravity force.
I was referring to the General Relativity Equivalence Principle:
Experiments performed in a uniformly accelerating reference frame with acceleration a are indistinguishable from the same experiments performed in a non-accelerating reference frame which is situated in a gravitational field where the acceleration of gravity = g = -a = intensity of gravity field. One way of stating this fundamental principle of general relativity is to say that gravitational mass is identical to inertial mass.Given our laser beam focus on the free will and the errors of Luther, it is a bit offtopic. The classic example is that the gravity one experiences in a static elevator at the earth surface is undistingushable from the inertial force in an accelerating elevator in the outer space. Gravity is acceleraion; the underlying physical reality is that either gravity or acceleration are different labels we put on the curvature of timespace. Likewise, in an accelerating car the observer experiences one curvature that pushes him and his coffee downward, formed by the mass of the earth, and he normally refers to that one as the earth gravitational pull; and the other curvature pushing him to the backrest of the seat and the coffee to the edge of the cup, created by the energy of the engine, and he normally refers to that one as inertial force. If instead of a car accelerating along the surface of the earth we had a car-shaped spaceship accelerating upward (toward the roof of the car) and pulled by a planet behind its hood, with a proper adjustment of the energy of that spaceship providing the upward thrust, and the size of the planet providing the rearward pull, we would have the exact same observations, even though the directions of gravity and acceleration have been swapped, gravity threatening to spill the coffee and acceleration securing it inside the cup.
The famous ontological equivalence of mass (source of gravity) and energy (source of acceleration) follows from this example.