According to their Facebook page, PNH Airport, from late September 2018, Phnom Penh Airport (PNH Airport) has declared to have new payment system for car parking. With the new payment system aka "SVAY Express Lane", which is designed for only drop off that will take less than 15 mn included. If you park more that these minutes, you are suggested to use normal car park system as the price for parking will be increasingly much more.
PNH Airport Car Park Payment Process
With the new payment system for car park, all users are required to 1) keep the ticket that received by parking machine at the entrance, then 2) they need to go to payment counter having new payment in place (recently a standby staff is out there to assist), before 3) they get in the car to leave the airport.
Below, it is the video we got from Cambodia Airport Facebook page:
Below, it is the video we got from Cambodia Airport Facebook page: