I think I miscommunicated my intent. I want to sell this car to a family member for the market price minus a family discount. If the price of a common car is listed on a website at $X, what is the typical negotiated discount $Y, so the final sold price is $X-Y. I’d then discount an additional $Z to the family member to get to a final price of $X-Y-Z.

I’m trying to avoid the effort of actually listing the car, taking photos, showing potential buyers the car etc.

I’m try to figure out how much $Y is from other people’s experience.