At this time you have neither a code problem nor a code question; what you actually have is a programming need, and the hardest part for the users here to help you with.
First thing you need to do is to identify what the actual need is
...to prepare the vehicle ahead of time and leap to the nearest exit where it will wait for the user...
Next thing is to determine what you have, and if it is sufficient
...we assume he will order it based on a 3 year history.
Great, you have a bunch of data to give to the pencil pushers
we want to study the regular users of the system and analyze their entry and exit times from the car park
Analysis is going to mostly a
business function. They will be determining how this is going to work and come up with the mathematics for it.
Once this is done, now you can start coding the solution.
1. You should be told how to figure out any users given in/out time
2. and how much lead time is desired for them.