by Mike Nicholes » Mon Nov 02, 2015 3:14 pm
The problem with GM (and everybody else's) calculation of 'turn' is that they use annualized cost of sales divided by the G/L inventory. This figure gives a 'ratio' and not the real number of times the value on the shelf 'turned'. The correct formula is 'true turn'; which is the turn figure they show times (X) the purchase efficiency; the purchase efficiency must be calculated by totaling up (and annualizing) three figures: 1. The parts bought on stock order from the factory; 2. Parts bought from other sources FOR STOCK to use on GM cars (or the brand you represent; and 3. All parts bought for use in the dealership that do not fit the factory cars you represent. The total of these three, annualized, gives the total dollars purchased efficiently (PE; purchase efficiency) times (X) the gross turn ratio. Now you have the number of times you turned your total investment. GM, or any other factory, does not know what you buy from other sources 'for stock' and what you buy that increases the cost of sales that are not your factory, but charged to the parts account.