My recollection of the "freewheeling " also known as "the automatic clutch" is roughly this. When the knob on the dash is pulled out, the car will free wheel (coast) when you let off the gas pedal. A large valved diaphragm with hoses and linkage is located alongside the engine starter. A vacuum tube is connected between the diaphragm and the intake manifold. When the dash knob is pulled out and you let off the gas, the increased vacuum in the intake manifold will move the diaphragm and a rod and will disengage the clutch. The car will then coast (freewheel) until you begin to accelerate. Once you accelerate, the manifold vacuum drops and the clutch will re-engage. Normal driving resumes. The automatic disengagement of the clutch will also allow you to shift gears without pushing the clutch pedal to the floor with your foot. You still need to push the clutch pedal in to start off or come to a complete stop. I once had a 34 Plymouth PE with a working automatic clutch. The action was very smooth, and it was interesting how it worked.