I believe that you may be barking up the wrong tree by focusing on the start-up price. First of all, if the changes you have made have not produced an increase in sales volume, average revenue or profit or a decrease in operating expense, then you haven't really improved anything.
You may want to first consider
marketing and promoting the wash and then consider what is necessary in terms of production and technology.
In today's economy, most consumers make purchasing decisions on the basis of convenience, time and value. For example, where is the closest store from where I live or work, how much time is involved with making the purchase, how much will it cost and can I buy it right now?
How does your store's value proposition answer these questions in relation to what the competition is offering in your region of influence and retail trade area?
You charge $1.50 for 3 minutes. If your average customer uses 2.3 cycles per wash, purchases a vacuum for $1.00 and one
vending item for $1.00, the total cost to wash their vehicle would be $5.00 plus the cost of their time to complete the work which usually takes at least 20 minutes without any waiting time.
How do you improve this business model? Internal cost controls can help but how do you increase profits once costs are minimized? In order to improve the model, you need to identify the things that you can do to reduce the total time and total (not incremental) cost of the wash or increase the customer's perceived value of your products and services. This involves
marketing and promoting the wash.