Servicing at least once a year, depending on how much mileage you do it could be more.
A 6+ year old car may have done a few miles - or a heck of a lot of miles. It may have a perfect service history and never been in an accident, or it could be a complete lemon
This, plus the fact we have no idea what make or model you are considering, does make it very difficult (= impossible) to predict maintenance costs.
Ferrari? Fiat? Ford? Lada? Rolls Royce?
You do realise all cars are different and there is no fixed price to run one..........
If some one could answer this question, they would never leave a "roulette table".
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I'm really thinking bout buying the car and I wanna know if it would be a good buy or bad and how much it would be in a 5 year range to own it and how often you have to get it serviced a year need answers !!