True Cost of Driving

I deliver pizzas and many pizza places under compensate drivers for their vehicles' miles. Most of the top three corporate pizza places get sued for it regularly. It is easy to determine the cost of gas per mile but how does one determine the typical life of all the need parts on average and with a fairly reliable range of life as it pertains to miles traveled. It is not easy to calculate the exact cost but have read it could be in the ball park of $2/mile or more plus gas. It is because nobody has determined a good and easy to understand way of measuring the cost of driving that drivers are so easily underpaid. Particularly since so many people don't tip well including people in dealerships ironically enough. Does kelly bluebook or anyone else keep data on the life of parts under normal use but as it pertains to miles?