When you end your Mevo trip, you’re given 200km free daily, The total distance allowance is based on how many days you had your Mevo, and then that’s compared with the distance you drove at the end of your trip. If you exceeded the allowance, each top-up km is $0.25.
In the real world, let’s say you picked a car up at 3 pm on a Friday and returned it at midday on a Sunday. Your distance allowance for the entire trip would be 400km. If you instead returned it at 4 pm on Sunday, you would have reached a new 24hr period so your allowance would jump to 600km.
It's important to note that your distance allowance does not add up minute by minute. It ticks over at the 24hr mark for every new day with your Mevo from when your trip began. For example, a trip started at 9am will get 200km added to its allowance at exactly 9 am the following day.