So I found a fix! The camera needed to be parented to the actual car geometry group, like bepe said, not the Cinema4D car rig "body." The wheels needed an octane tag with motion blur set to transform/vertex, and the body geometry (separate from camera) needed an octane tag as well!

I'm having an issue with motion blur on a moving car not working correctly. The motion blur is being adding to the entire car, not just the wheels and the background.

I have a car model rigged with the Cinema 4D character rigging tool. The octane camera is a child of the car so it moves with it. I ...