I think the IRS allows something like . 48c per mile for autos. Do we have any useful data for our diesel rams? Of course there are fixed costs of license and insurance, etc. But I have loaned out truck and he pays fuel but after xome 3600 miles plus, we need to have some acceptable real value. Tires aren't too hard to estimate and oil and lube every 5-7500 miles, and of course increased milage has its own devaluation of resale not to be reminded of the other wear such as brakes, belts, etc. Recouping insurance and license is not needed, but other running costs and milage depreciation, minus fuel paid by him, will be the number needed. thanks for any data. Larry