# Sharing a car with a friend: how to split the costs Canonical URL: https://www.evenoutapp.com/guides/sharing-a-car-with-a-friend Updated: 2026-10-06 Split a shared car in two parts. Fixed costs, like the loan payment and parking permit, are owed whether or not the car moves, so split them by ownership. Running costs, like fuel and tires, follow the miles, so split them by each driver's odometer miles. Add the two parts for each person's monthly total. Key points: - Fixed costs go by ownership share and running costs go by miles, so a person who drives less pays less. - With $430 a month fixed and $0.20 a mile, drivers of 800 and 400 miles pay $375 and $295. - Put a small repair fund in by ownership share, and split big repairs by ownership share too, not by who was driving. - Agree a notice period in advance, because the fixed costs keep running after one person stops using the car. ## How do you split the costs of a shared car? Split them in two parts: what the car costs to own and what it costs to drive. The ownership part is owed every month and goes by each person's share of the car. The driving part rises with the miles and goes by who drove them. A driver who covers 400 miles pays less than one who covers 800, and nobody pays for miles they did not drive. This page covers the money only. Who goes on the title and the insurance policy, and who is responsible after a crash, are questions for your insurer and your local motor vehicle office, not for a cost split. ## What counts as fixed and what counts as variable? Fixed costs do not change with the miles. Variable costs do. - **Fixed:** the loan payment, the insurance premium, registration and fees (set aside a twelfth of the yearly bill each month), and a parking permit. - **Variable:** fuel, oil changes, tires and routine upkeep. Say Dana and Eli own a car together, 50 and 50. Their fixed costs are $270 for the loan, $120 for insurance, $10 for registration and $30 for a permit. That is $430 a month, so each owes $215 before anyone turns a key. ## How does the odometer method work? Each person pays half of the fixed costs plus a set price for every mile they drove. To find the price, add up a few months of fuel, oil, tires and upkeep and divide by the miles. Say the last three months cost $540 over 2,700 miles. That is $0.20 a mile. Here is a month where Dana drove 800 miles and Eli drove 400. | Driver | Fixed share | Miles | Mileage cost | Month total | |---|---|---|---|---| | Dana | $215 | 800 | $160 | $375 | | Eli | $215 | 400 | $80 | $295 | | Both | $430 | 1,200 | $240 | $670 | The check: $430 fixed plus $240 of mileage is $670, and $375 plus $295 is $670. Dana pays $80 more than Eli because she drove 400 more miles at $0.20. To make the miles checkable, take a photo of the odometer or write the number in a shared note each time the car changes hands. At month end, subtract the start reading from the end reading for each driver. ## What if you own different shares of the car? Let ownership set the fixed part and miles set the running part. Say Dana owns 60 percent and Eli 40, and the fixed bill is still $430 a month. Dana owes $258 (60 percent) and Eli $172 (40 percent). The mileage cost is the same as before. - **Dana:** $258 plus $160 for 800 miles is $418. - **Eli:** $172 plus $80 for 400 miles is $252. Together that is $670 again. The ownership split changes who carries the fixed costs. It does not change what a mile costs. ## How do you split a repair? Use a repair fund for small jobs and ownership shares for big ones. Each month each owner puts a small amount aside in an account you can both see, by ownership share. With a $50 monthly fund and a 60 and 40 split, Dana puts in $30 and Eli $20, so the fund holds $600 after a year. Then a $900 repair arrives. The fund pays $600. The other $300 goes by ownership share: $180 from Dana and $120 from Eli. A big repair follows ownership, not who was driving, because nobody can say which mile broke the part. ## What happens when one person stops using the car? The fixed costs do not stop, so agree a notice period before you buy in. Say it is two months. If Eli stops driving on March 1, he owes $215 for March and $215 for April, and no mileage because he drove none. From May, one of you takes the car on, or you sell it and divide what it brings by ownership share. Write the notice period and that rule in a note both of you keep. ## How do you track it in EvenOut? Make a group for the car and record each cost where it belongs. 1. **Fixed costs.** Add each as an expense, "Split equally" for 50 and 50, or "By percent" for 60 and 40. Under "Photo, repeat, pending or note", set Repeat to Monthly. 2. **Running costs.** Once the month's odometer readings are in, add each fuel or upkeep receipt with "By shares" and type each person's miles as the shares, 800 and 400. A $240 total comes out as $160 and $80. Put the readings in the note. 3. **Settle up.** Record each payment in "Settle up" and watch the balance show who is square. ## What to do next For a car shared on a schedule, such as a weekday commute, [how to split carpool costs](https://www.evenoutapp.com/guides/how-to-split-carpool-costs) covers fuel, tolls and wear per rider, and the [carpool cost calculator](https://www.evenoutapp.com/tools/carpool-cost-calculator) runs the numbers. Another asset where ownership and use differ is covered in [co-owning a boat](https://www.evenoutapp.com/guides/co-owning-a-boat-costs). ## Frequently asked questions ### What do we owe in a month when nobody drives? The fixed costs still come due. With $430 a month fixed and two equal owners, each owes $215 and nobody owes any mileage. The running cost is zero because the odometer did not move. ### How often should we update the cost per mile? Every quarter, or when fuel prices move. Add up fuel, oil, tires and routine upkeep for the period and divide by the miles driven. If 2,700 miles cost $540, the rate is $0.20. If fuel rises from $3.60 to $4.20 a gallon on a car that does 30 miles a gallon, the fuel part goes from $0.12 to $0.14 a mile. ### Can a friend who is not on EvenOut be part of the car group? Yes. Add them as a guest by name in the group, track their share now and invite them later to claim their spot. Their shares move to their own account when they do. ### Does EvenOut move the money between us? No. EvenOut records who paid and who owes. Settle up records a payment between you, including a partial one, but you pay each other outside the app.