Car rental, decoded
Rental day
Also known as: 24-hour day, rental period
The 24-hour unit a rental is charged in, counted from pickup time. Returning past the hour it started, beyond any grace period, typically triggers another full day's charge.
What you may think
A day means a calendar day.
What is actually happening
A rental day is usually 24 hours from pickup, so a late-afternoon return the next day can count as two days.