Stretching a rental car week?
 

I have flights arriving at 10:30 and leaving at 2:30 the following week.

Any ideas about how to avoid adding an EXPENSIVE single day of rental onto a weekly rental. I know I can sit in ORD but I don't want to.

How wide can I stretch a week before I get hit with an hourly or daily charge?

I'm thinking about reserving noon-noon and having actual times of about 11:15-11:30 until ~12:45.

Will starting early move up the week long ticker?

I assume there is a 59 minute return grace period?