Faced this issue a few years back.
The old system was similar to what you are using: flat rate commission for detail, etc.
The motivation is pretty clear: get as many cars detailed as possible to earn more money. System works o.k. for the techs, so it should work for detailers, right?
Well, assuming you want a clean car on the line and every car is detailed prior to being put on display (new and used). What happens if you need to detail the car again, say at delivery? Do you charge car again? Who pays?
It grew to a crisis since the managers wanted to charge the work to internal without any recovery.
So, we went off the flag system and pay everyone in the dept. by the hour. We hit every car (even w/s junk) $100 ONCE and use that fund to pay the detailers and get-ready manager. Now, we can detail a car several times and thru the years the fund balances pretty close. Obviously, if it becomes out of balance, we can adjust the charge.
The tough part is personell issues. To be fair, we calculated the hourly rate using the annual earnings of the detailers divided by the clock time they worked. But they were not very productive (ha!) and we replaced them. The current team has been with me for 5 years and everything works smoothly. The goal is to keep everyone busy doing something.
scott
ps. some of you may notice that this is a change from my normal 'compensate based on productivity', but we have much, much higher quality with this process and believe me, every car gets proper attention.
Your pack may be different. Figure it this way: Divide your total get-ready pay for last by the number of cars sold (new/used and w/s). I'd adjust it up 10% to be conservative.
[This message has been edited by sallen1 (edited 01-25-2002).]