Like Earl said, there is a lot to consider.
For example, when convenience store owners select a drink fountain, they begin with sizing and consider geographic location, space configuration and customer volume.
A 4 + 1 built using this process would imply the market may not be particularly strong for automated washing. Otherwise, you would think something else would have been built.
If the plan is a 120’ conveyor, this would mean you are anticipating at least 75,000 washes or more annually. If you are not, a 120’ conveyor would be a mistake.
If you anticipate the need to wash, say, 30,000 vehicles annually, a mini-tunnel or in-bay express might make sense.
I have a client in the Midwest that just converted from in-bay to express wash, no downsides.
Revenue depends on market and management.
Some developers build inexpensively in lower income areas and aim low, $3.00 to $10. You might average $7 a wash and would need to wash a lot of cars.
If you take the high road, an average of $10 is very doable.