Every car through the tunnel drinks a few ounces of presoak, soap, wax, and drying agent. Cost each line per car, SUM the stack, and you know the chemical cost behind every wash.
Presoak, soap, wax, and drying agent add up to $0.32 per car — against a $12 ticket, chemicals are under 3%.
The example
Each chemical's ounces per car and cost per ounce, with a per-car cost line.
| A | B | C | D | |
|---|---|---|---|---|
| 1 | Chemical | Oz / car | $ / oz | Cost / car |
| 2 | Presoak | 5 | $0.02 | $0.10 |
| 3 | Foam soap | 3 | $0.03 | $0.09 |
| 4 | Spray wax | 1 | $0.08 | $0.08 |
| 5 | Drying agent | 0.5 | $0.10 | $0.05 |
| 6 | Total per car | $0.32 |
The formula
Each line is ounces times unit cost; the total is a SUM:
How it works
Two layers of the same idea:
B2*C2costs one chemical per car: ounces used times dollars per ounce.- Copy that down the stack — every chemical gets its own per-car line.
SUM(D2:D5)adds the stack into the total chemical cost per vehicle.
Get $/oz from the drum: a $180 30-gallon drum is $180/3840 oz ≈ $0.047 per ounce of concentrate.
Try it: interactive demo
Enter ounces per car and cost per ounce for two chemicals.
Variations
Cost per 100 cars
Scale the per-car total to a day's volume.
Chemical percent of ticket
Divide the per-car cost by the average ticket.
Pitfalls & errors
Cost the diluted ounces actually sprayed, or cost the concentrate ounces — but never mix the two in one line. Titrate to know your real usage.
Re-titrate after any pump or tip change; a worn tip can quietly double the ounces per car on one arch.
Practice workbook
Frequently asked questions
How do I know ounces per car?
What should chemicals cost per car?
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