Kenneth,
Sounds good. However, the $2,500 per year cost of depreciation is most likely in addition to the trade-in value (cost) each year. If that is the case, that trade-in value is a cost that had to made at some time in the past, and that trade-in money/cost is not available for something else now.
I do the same thing, with the same rationale, in buying a minivan every three years at the end of a model year and keeping it for three years. Up here, I'd need a covered pickup in order to get any use out of it during the winter. Also, my minivan gets 20-25mpg, depending on the type of driving.
I also completely agree with you about the reliability and comfort of modern vehicles relative to any old vehicle, even if the old vehicle is in excellent condition.
Nonetheless, if I could only afford one vehicle, and I did not have a significant amount of money to put into a down payment (on two vehicles - a new one and a classic one), and I lived in a warmer climate, and I was willing to keep up with the easy/inexpensive maintenance needed on these old trucks, I think I could make a economically valid argument that the total cost of ownership of an old truck as my only vehicle is at least no worse than buying a new vehicle every 1-3 years.
Also, I would only need a one vehicle garage.
