Estimate annual driving costs.
Annual driving cost splits into two behaviours. Mileage-driven costs — fuel, tyres and servicing — scale with distance and shrink if you drive less. Fixed costs — insurance, road tax and the bulk of depreciation — land whether the car moves or not. Separating them answers the question people actually have: for a low-mileage driver the fixed share often exceeds two thirds of the total, which is when giving up the car and renting occasionally starts to make arithmetic sense.
Mileage costs
Fuel = miles / mpg x price; maintenance = miles x cents per mile / 100
Annual total
Total = fuel + maintenance + fixed annual costs
Mostly. Age drives more of a car's value loss than mileage for typical use, though beyond about 15,000 miles a year the mileage component becomes material and is better modelled as a per-mile figure.
Around 8 to 12 cents for an ordinary petrol car including tyres, brakes and servicing. Premium and performance models run considerably higher; electric cars run lower because there is far less to service.