The OP asserts (I agree) that the real profit from running a car wash is not the daily turnover of car washing, but the capital appreciation of the land the car

The OP asserts (I agree) that the real profit from running a car wash is not the daily turnover of car washing, but the capital appreciation of the land the car wash sits on. The part about leverage assumes you are able to get a loan/mortgage to purchase the land the car wash sits on. In effect you are using the car wash as a reason to justify a mortgage you wouldn't otherwise be able to get for real estate speculation alone.