WheelCollider slowing vehicle down at 0 torque

I have connected several wheel colliders to an object and applied a torque to them. Now, when I apply a torque of 0, it would reason to be that the wheel would continue spinning until some kind of force was applied to it. unfortunately, it seems to produce its own, ghost braking torque. Where could this be coming from? I am attempting to make a semi-simulator, so I was hoping to simply use the friction models and deal with applied torque on my own.