You have to get to the rental cars by taking the shuttle. I have always seemed to get great help at the front desk. Really appreciate the touch screen rental agreements versus signing all the papers.
it is quite a walk from inside to the car lot, but that is because it was quite cold and windy when I visited. I had no issues with the car, but must be careful when returning. the car rental return is not at the same exit as the airport, so you will need to exit the airport to return if you do this.
Spoken from experience.