Road-trip car

We're planning a long road trip for when we retire, and we don't normally keep a car. So which one is worth buying just for the trip, and what do we lose when we sell it afterward? The sticker price barely matters. What a car costs is the gap between what you pay and what you get back, plus financing, insurance, registration, tires and fuel in between.

The first view models the whole arc: buy, drive, sell, with a cost curve for every possible sale month, in nominal dollars and in today's purchasing power. The second prices the financing. Instead of an auto loan you can sell an SPX box spread - four option legs with a fixed payoff, which is really a loan against your portfolio at close to the risk-free rate. It lays out the cash you collect, what you repay, the effective APR after fees, and the margin, option-style and tax rules you have to meet before trying it.