Then there is the cost of depreciation, or, if one is lucky or bought wisely, appreciation, of course. This is probably of more interest to owners of more expensive cars than a £500 V70, but the way I treat this is to take the purchase price, subtract the sale price, giving the cost of ownership. Divide this figure by the period owned or the miles covered to give the depreciation per year or cost per mile respectively. Remember, this could be a negative figure if you are selling at a profit.
This is not the total cost of ownership, of course. One must add in lost interest on the capital employed, or, if one has taken on a loan, factor in the interest charged. In this way, it is possible to arrive at a total cost per mile at the point of sale by adding this cost to the cost of operation calculated above.
Remember that your car is still costing you money even when it is standing idle on your drive - a lot of people overlook that!
You may think that I am mad - that's fine - but I do derive a strange fascination in accurately calculating the true cost of my motoring.
Regards, John.