Pre-paid, no contract, monthly cell phone plans are popular because bandwidth is huge, ubiquitous and everyone in a firm or family can have their own cell phone to talk and text.
However, as Gearhead implied, a single in-bay automatic has no such advantage.
Do the math.
Many express washes sell unlimited for $19.95. Think about what this means for an in-bay that washes 12,000 cars per year, average $7 or $84,000 sales revenue.
12,000 CPY is equivalent of 3,000 customers each washes an average of four times a year.
12,000 CPY = average 39 CPD = average 3 CPH = peak 9 CPH
Peak 9 CPH means when wash is most busy, 40% of time there will be four cars in waiting line.
If you sell 100 unlimited plans and each customer washes “average” of five times a month, that’s 6,000 washes per year (100 * 5 * 12).
CPY = 6,000 + (2,900 * 4) = 17,600
Total sales revenue = (100 * $19.95 * 12) + (2,900 * $7 * 4) = $105,140
17,600 CPY = average 56 CPD = average 5 CPH = peak 15 CPH
Peak 15 CPH means when wash is very busy, length of waiting line and waiting time will be exceedingly long leading to balking and line abandonment.
If you sell 200 plans, total CPY = 23,600 and sales revenue = $129,080
23,600 CPY = average 76 CPD = average 6 CPH = peak 18 CPH
Peak 18 CPH implies even greater balking and line abandonment.
As the level of balking and line abandonment increases, the likelihood decreases of reaching the anticipated or projected annual sales volumes and revenues.
What would be a realistic anticipated or most likely outcome?
AO = (129,080 + 105,140 * 4 + 84,000) / 6
AO = $105,600
$105,600 - $84,000 = $21,600 gain
Estimate the “total cost” to design and implement unlimited at in-bay and you can calculate risk reward, sanity, viability, etc.