In Victoria the Trade Practices Act would cover this. From memory s71 deals with merchantable quality. In essence (provided this is not a purchase for business use) the car must be merchantable quality. For example, if you went to a car yard and they had hail damaged cars and they sold you a car at a discounted rate because of the damage, then it is merchantable in the circumstances.
If you purchase a new car and paid a price reflecting this, then you were provided with a hail damaged car (regardless of repair) you would argue that the car is not merchantable quality in the circumstances.
I am not sure what similar laws would apply in WA, but as already stated I would want to confirm that the car was not damaged and repaired before taking delivery. I vaguely remember a case where a new car was purchased and there was some damage done prior to delivery. The dealer repaired it. It was later discovered (some time later) and it was argued that it was not a new vehicle. This argument failed as the car had no prior owner and therefore was a new vehicle. The argument should have been that the car was not merchantable quality.
Note: this is from a vague memory so don't take this as advice by any means, I just hope it helps you on the right path.
good luck and GOLF IT UP!