Here's the idea -

I have a car held with Hertz for the solar eclipse, but of course it's just the normal no prepayment booking through their webpage.

Is there any way to prepay this, and have it "locked in" to more guarantee that a car will be there when I walk up? My worry is that given the demand that weekend, they will screw something up and I'll be left with no car. All the more exacerbated by other people booking multiple cars, etc and completely screwing up the usual show/no-show estimates these companies use.

Any possibilities, or would it even make a difference?

Thanks!