The contractor who poured our pad did not put any slope on it, so
water just comes in around the doors or from the car and sits on the
floor instead of running back out.

Your real problem was the contractor. I don't know of any idea that
will always work.

I know... They came recommended and weren't the lowest bid. It was like
pulling teeth just to find a contractor who was interested in the first
place.

I'm just trying to make the best of the situation.