I had the same experience.. maybe the same old businessman. He told me that the secret to his success was always getting back to people.Years ago I had the opportunity to ask a very successful, very old, famous businessman what the secret to making money was. He simply said " sell it for more than you paid for it". At first I thought he was being a smart ass. He then went on to say that it is only possible to do that when you know exactly what you paid for it. Once you determine your "total cost" you simply have to price it accordingly. If the market you are in will not pay more than it costs you, then you need to either lower your costs or find another business. Transportation is a little tougher since we live in a world where we quote fixed pricing and deal with variable costs with every load.
Knowing a number as accurate as possible to calculate your true cost is critical. A cost per mile number is only accurate if you include every cent of your total cost. Too many carriers base their cost per mile on operational costs only. Once you add in all administrative costs, all building costs, all management, all taxes, all travel and entertainment, and every single dollar that is on your monthly P&L and then divide by miles driven you will then have an accurate number.
And since this number will change monthly and seasonally you need to average it out over at least 5 years to have a number that makes sense.
I think any way can work if you use it properly. Cost per mile that only includes direct costs (fuel, driver salary, maintenance) is perfectly valid if you're trying to determine the potential contribution of a given load. It will tell you how much is available to service your other operating costs or fall to the bottom line as the case may be. Your approach also works; the information provided is not exactly the same, but can be useful nonetheless.A cost per mile number is only accurate if you include every cent of your total cost. Too many carriers base their cost per mile on operational costs only.