Pre-1997, I owned a QS lube, full-service wash with detail center. Good business until race riot and burning down of houses. Then the local tire centers began selling oil changes for $9.95 to sell tires and stay in business. I also supervised oil change while employed by a carwash chain. I also managed gasoline station and repair shop back in early 70’s.
When working with veteran operators having a multiple facilities carwash, I usually find the issue is not how to create more transactions (selling more stuff mentality), but rather how to create more value for customers. In other words, if you can offer customers more value, they will buy more and more often.
Generally speaking, operators of such multiple facility sites find it useful to create more value through customer
loyalty programs. Combined with a good virtual experience (website), this can create enormous
marketing power.
Hopefully, this helps and satisfies your doubting Thomas.