its purpose IS to be stepped on, thats why its ribbed, to get traction for stepping in and out of the car.No, I mean the lateral (not longitudinal) sort of ribbed cossmember that one steps on (accidentally) as they enter/exit the car. It appears to go under the sills, but I have no idea how it's terminated.
i suppose you could "buff" it out?? or something. or (horrid!) carpet over it