In response to Cowboys example of the car sales person not mentioning how much the car with interest payments add up too He simultaneouly did not mention the opportunity cost of capital you have when you are able to put the same money to work for yourself.
If I pay 6% on a loan but I earn 10% on my investments then the car cost less. If I lose 10% the car costs more. To try and simplify the matter to adding the payments and subtracting the cost could be a pretty costly mistake.
