Q. "I want to set it up so that my customers can rent for less than 24 hours but still be charged for one full day. Is this possible?"
A. In short, yes, it is possible. Here's a simple guide how to set it up in just a couple of minutes.
1. Add a new pricing scheme OR open up an existing pricing scheme.
a) You can name it however you like. I've named mine "per day" since I have a daily price of 35 Euros per day.
b) Take a look at the first date range "from 1 to x" (It doesn't matter if the pricing scheme is from 1 to 1, from 1 to 6, from 1 to 100.. etc). The price you have listed (in my case, 35) is the price for a 1 day rental.
c) set the pricing scheme to active
2. Create a new "sister" pricing scheme.
a) This pricing scheme will be associated with the pricing scheme you made in step 1.
b) You can name it something helpful. I named mine "Per Hour Pricing". If you have many pricing schemes, the name could be: Step 1 - "Compact Pricing - 1", Step 2 - "Compact Pricing - 2" or step 1 - "Compact Pricing - Daily", step 2 "Compact Pricing - Hourly"
c) Skip over "day ranges" pricing! It's absolutely important you leave this blank.
d) Click "Septup the hour ranges"
e) Set it up like in the picture: From 1 to 24 price per hour - [24 hour Price] - It's the price I mention in step 1.b. In my example, it's 35.
f) If you want to have a minimum amount of hours, you can set it "from 5 to 24.." etc. Just make sure it's until 24 hours. You can also change this setting for each individual car by creating a minimum rental time in hours.
g) Set the max total price to the same price in step 1.b and in 2.e -> don't forget this step!
h) Set the pricing scheme to active.
3. Add both pricing schemes to any cars you want with this scheme.
a)You need to add them both!
4. Head over to translations, select your language (including English), and change "Per Hour" to "Per Day" for each language.