When comparing prices for Tahiti a few days ago, Hertz was showing me rates with unlimited km. Now it will only show rates with 0km and a quite expensive cost per km that will work out a lot more costly even though I won't be going far.

Is there any setting or rate code or even any logic to getting unlimited mileage rates or is it just down to the whims of the local agency / day of the week / direction of the wind?