Daily car hire is a Service type that allows you to rent cars similar to rent-a-car service but with or without an assigned chauffeur to the car. 
In Car management when you set "Use for Daily hire?: Yes" the car will be available for Daily hire and this booking type will automatically appear in the Service type drop down at the booking form.
There will also be a few options that you can set up here:
Weekday price: - a mandatory field that set the daily car hire for week days (not weekends) in 24 hour day period. 
Weekend price: - with this option you set up the price that will be set during the weekend. You can set both weekday and weekend price the same.
Special day price - you can even have special prices for different days of the year. The system will automatically detect and calculate collective price of the whole hire period. 
- Date: - select date for Special date pricing.
- Price: - set the price for that Special date.