My experience with EZ Car Rentals turned out to be okay in the end. The speed of return was like it sounds, easy. Upon arrival the staff quickly checked the car and within 3 minutes the shuttle driver was ready to get us to the airport. The whole process this time was about 10 minutes and that included a quick stop to another lot for EZ Car Rentals.
Word of advice: You should still arrive at EZ Car Rentals at least 30 minutes before you want to arrive at the airport because you may arrive at a time when the shuttle is not ready to go. If I had arrived a couple of minutes later, I would have waited at least 20 minutes. I believe they only have one driver and this driver is also picking and dropping off guests for their partner hotel, NU Hotel.