The bolded has been my experience over several rentals in the past. However, I'm not sure what the "in addition to what the rental costs" means - unlike other airline miles, RR points earned in connection with a car rental are flat - i.e., a $19/day rental = 600 points...but, a $109/day rental also = 600 points.I did some reading into it and only 600 bonus points would count no matter what the total bonus is. So for a 1 day rental you would receive 600 bonus points (on top of what you spend), but for a week rental you would get 2,400 points bonus. However only 600 points would count towards companion pass in addition to what the rental costs.