I believe you need about 1000 unlimited customers to make a plan viable. Everyone always concentrates on the customers that wash their car multiple times a month and how much money you lose on them . The trick is to sign up enough customers that not all of them will use it everyday some will just use it twice a month. We have average usage of 4.5 times a month and that is high. The EE with 3-4000 members are lower than that.
I would not try to run an unlimited program without an attendant there to sell and take care of the club customers.
With that being said there is a group using the Petit auto's that do very well unattended and have an unlimited plan everything is handled through the auto cashier and an
app. A lot of my customers are not techy enough to do that and need a person to do it for them.
Our wash was not always unlimited we just started that 2 years ago with the install of the new Petit auto's. There were a few hiccups to start but we worked through them and now it is relatively easy.