Some vehicles not auto-recalling after time is up
Sedan seems to be the big culprit.  Not sure if the minicopter does as they do spawn naturally too.  But I have cars litering the landscape because people never recall them.  And my settings appear correct ...

{
  "Define your licence settings": {
    "Interval in minutes to check vehicle for wipe": 5,
    "Time before vehicle wipe in minutes": 15,
    "Use Economics to buy vehicles": false,
    "Use ServerRewards to buy vehicles": true,
    "Shortname of item needed to buy vehicles": "RP",
    "Use permissions for chat commands": true,
    "Use Raid Blocker": false,
    "Use Combat Blocker": false,
    "Remove Vehicles On Crash": false​
PRETTY PLEASE?  The cars all over the land look like the begining of The Walking Dead

as funny as that sounds that could be annoying. Maybe a temp work around could to use timed execute (free universal plugin from UMOD) and set it up for example as follows:

 

say: "Server is cleaning up all cars on the server. Type /recall sedan to recall your car to prevent it from being deleted."
run command to delete all sedans on server
say: "Server is done cleaning up cars, you may now respawn your car with /spawn sedan"

But how would I delete all cars?  There's no command I know of for that