$80/month is pretty high for registration and insurance but it does depend on location. My registration and full coverage on my car costs $33/month and half that on my truck with liability. Also you are only including the cost of gas, not of wear and tear on the truck which will have a much higher price tag when it comes for replacement, especially if you are driving on salt laden roads in the winter time. The overall cost of ownership of a truck is much higher than that of a car and the numbers do prove this out, especially which you include purchase cost. If the truck is paid for and you'd like to hang onto it for a long time I'd say you'd be money ahead to buy a small commuter car in most cases not to mention for longer trips and general day-to-day driving. And honestly how much depreciation can you expect on a sub 5k car? The truck is going to have far more depreciation by driving it as pickups tend to have more resale value, especially diesel pickups.