There's a carwash down the road from where I work. Every day I drive by, and every day the price advertised for a wash is different.
The weird thing is, it doesn't necessarily seem to be related to the weather. It could be cheaper on a sunny day, or more expensive. You never know. The most expensive day I saw was on an overcast cloudy day that looked like it was threatening rain.
Also, it's not like it just goes up a buck or two -- you know, the normal "special" type of deal where it shifts from $6.99 to $5.99 and then back. This place is all over the map. One day it is $6.45. The next day it's $4.75. The day after, it could be $5.59.
I must learn this secret and forbidden car wash formula.
I believe I am close to a breakthrough. From my calculations I have determined that it seems to be a complex equation based upon the 3-day accu-weather forecast, the current price of carwash soap futures, the daily smog index, and the hourly wage being paid to the off-season migrant farm-worker manning the booth that particular day.
Either that, or they're just putting the numbers up on the sign in whatever order it is that they come out of the box.
The next time I get my car washed, I'm going to ask.
Call it my need to know.