A second car that's paid off still costs money every month — insurance, registration, upkeep, the value it loses each year. The question isn't whether it's expensive. It's whether it costs more than the rides, rentals and extra miles on your other car that would replace it. Put in both sides and see.
The second car usually escapes scrutiny because it has no payment. But AAA's 2025 estimate puts the cost of owning a new car at $11,577 a year, and only $1,131 of that is finance charges. The rest — depreciation, insurance, registration, fuel, maintenance and tires — keeps going after the loan is gone.
An older paid-off sedan is far cheaper than that average, but rarely cheap. $110 a month of insurance, $250 of registration, $900 of upkeep and 12% a year off a $9,000 value comes to about $296 a month before you put a drop of fuel in it. Add 500 miles of driving and it's roughly $373 a month — close to $4,500 a year.
Most second-car trips aren't lost when the car goes. They get combined into the other car's errands, shifted to a schedule that works, walked, biked, or dropped altogether. What's left is a handful of trips a month that genuinely need a ride, plus a few weekends a year when both of you need wheels.
At the default inputs — eight $18 rideshare trips a month, four rental days a year and 150 miles moved onto the other car — the replacement costs about $205 a month. Against $373 for the car, plus the interest on $9,000 of freed cash, the one-car household comes out about $2,400 a year ahead.
The figure that decides it is the number of rideshare trips you can absorb before the savings vanish — the break-even row above. With the defaults that's about 19 trips a month. Well under it, selling makes money. Well over it, the second car is earning its keep.
Two situations change the answer more than any other input:
Selling an underwater car means paying the difference between the sale price and the loan balance in cash. The calculator shows that as negative cash freed. It doesn't change the monthly saving — the payment, insurance and upkeep still disappear — but it does mean you need the gap in hand to sell, or you'll have to roll it into a personal loan, which rarely makes sense.