You will see that cars have both hourly and daily rates.
The hourly rate applies for each hour you have the car, until you reach the daily rate (usually 5 hours). The daily rate would apply for any booking of between 5 and 24 hours, meaning that the daily rate is the most you will pay for the car in a 24 hour period.
For example, if the car costs $5 an hour or $25 a day, you will be charged for each hour up to 5 hours (5 x $5 = $25) and then the rate will be capped at $25 for the remainder of that 24-hour period.
This would apply to any 24 hour period from the time your booking started. So for example, 9am one day till 9am the next day is a 'day' for the purpose of calculating the rate.
This makes Car Next Door vehicles really economical if you need to get around town for a day (or more)! Check out this cost comparison against car rental and other traditional car share options.