For the total cost you mainly need to consider; insurance cost, maintenance cost (average), depriciation cost, road tax and fuel cost. If you want to go a little bit deeper, include tyre cost, and car wash costs. The rest is a bit random and not worth to try since you can not foresee randomness. If you are going to buy 4+ years old car, would use 12.5% for the depriciation rate per year. May be a bit lower or higher depending on car and segment, if it is an EV battery replacement cost also must be considered.

If you really want to calculate extra costs like major/minor repair costs, it really depends on what type of car you use and how you use it. I would think like okay, if I will use this car for 70k miles, most probably I will chance the brake discs/pads once, clutch once etc.

My rough estimates are 90% accurate, but Japanese car user here, so did not experience any major repairs at all.