What to consider in Turnover

I have a query related to turnover. Dealers of used vehicle are working on two type of business model. One is Inventory, in which they purchase vehicle and sold to customer. I this case, sale price of used vehicle is become part of turnover.
Whereas, second is "Park and Sell", in which dealers charge commission from seller for facilitating him in sale of used vehicle.
My question is that what would be turnover for dealer in case of commission business, Sale Price of Vehicle or Commission ?